Mobile body

ABSTRACT

A control device ( 60 ) of a mobile body ( 1 ) calculates a center-of-gravity displacement degree index value representing an estimate of the degree of displacement of the center of gravity of the operator in the lateral direction of a vehicle body ( 2 ) from a predetermined reference position with respect to the vehicle body ( 2 ), and determines a control input for an actuator ( 15 ), which can cause a moment in the roll direction to act on the vehicle body ( 2 ), so as to increase the degree of displacement of the center of gravity of the operator indicated by the center-of-gravity displacement degree index value in a state of presence of such displacement. The control device ( 60 ) controls the actuator ( 15 ) in accordance with the control input.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile body (mobile object) such astwo-wheeled vehicles.

2. Description of the Related Art

Conventionally, for example, two-wheeled vehicles equipped with anactuator which generates a driving force for steering a front wheelserving as a steered wheel are known, as seen in Japanese PatentApplication Laid-Open No. 2013-060187 (hereinafter, referred to asPatent Literature 1), Japanese Patent Application Laid-Open No.2011-046342 (hereinafter, referred to as Patent Literature 2), etc.

Further, for example, three-wheeled vehicles having a pair of right andleft rear wheels and configured to allow the vehicle body to be rotatedin the roll direction with respect to the rear wheels by an actuator areknown, as seen in Japanese Patent Application Laid-Open No. S59-149878(hereinafter, referred to as Patent Literature 3) and Japanese PatentApplication Laid-Open No. 2005-088742 (hereinafter, referred to asPatent Literature 4).

SUMMARY OF THE INVENTION

In a mobile body as seen in any of Patent Literatures 1 to 4, duringstraight traveling of the mobile body, an operator normally sits on aboarding section of the vehicle body in the state where the center ofgravity of the operator is located approximately on the plane ofsymmetry of the vehicle body orthogonal to the vehicle width direction(when the vehicle body is considered to be bilaterally symmetrical).

On the other hand, upon turning of the mobile body, the operator mayintentionally shift his/her weight with respect to the vehicle body suchthat the center of gravity of the operator is displaced from a positionon the plane of symmetry of the vehicle body (position in a so-called“lean-with” state) to the right side or left side of the vehicle body(to attain a so-called “lean-in” or “lean-out” state).

The lean-in state refers to the state where the center of gravity of theoperator has been displaced, from the position in the lean-with state,relatively with respect to the vehicle body in the same side as theinclination (to the right side or left side) of the vehicle body. Thislean-in state is advantageous in that it ensures good gripping of thetires during turning of the mobile body or facilitates turning at highspeed, so the lean-in state is often used when turning on a slipperyroad surface or when turning at high speed, for example.

The lean-out state refers to the state where the center of gravity ofthe operator has been displaced, from the position in the lean-withstate, relatively with respect to the vehicle body in the opposite sideto the inclination (to the right side or left side) of the vehicle body.This lean-out state facilitates banking of the vehicle body duringlow-speed traveling, so the lean-out state is often used when turning ina small radius.

Further, the lean-in or lean-out state may often be used depending onthe operator's preference on how to operate the mobile body.

It is considered to be desirable that the lean-in or lean-out state canbe attained quickly when the operator shifts his/her weight with respectto the vehicle body trying to achieve the lean-in or lean-out state.

In view of the foregoing, it is an object of the present invention toprovide a mobile body which can quickly realize a lean-in or lean-outstate when the operator shifts his/her weight in an attempt to achievethe lean-in or lean-out state.

The mobile body of the present invention is a mobile body which includesa vehicle body having a boarding section for an operator and freelytiltable in a roll direction with respect to a road surface, front andrear wheels disposed spaced apart from each other in a longitudinaldirection of the vehicle body, an actuator capable of causing a momentin the roll direction to act on the vehicle body, and a control deviceconfigured to control the actuator, wherein the control device includes:

a center-of-gravity displacement degree index value determining sectionwhich determines a center-of-gravity displacement degree index valueusing an observed value of a motional state of the mobile body, thecenter-of-gravity displacement degree index value representing anestimate of a degree of displacement of a center of gravity of theoperator seated on the boarding section in a lateral direction of thevehicle body from a predetermined reference position with respect to thevehicle body; and

a control input determining section which determines a control input forcontrolling the actuator in accordance with the determinedcenter-of-gravity displacement degree index value in such a way as toincrease the degree of displacement of the center of gravity of theoperator indicated by the determined center-of-gravity displacementdegree index value in a state where the center of gravity of theoperator seated on the boarding section is displaced from thepredetermined reference position, wherein

the control device is configured to control the actuator in accordancewith the determined control input (first aspect of the invention).

It should be noted that the mobile body of the present invention is,more specifically, a mobile body which has a characteristic that, in thetraveling state of the mobile body, a turning behavior changes inaccordance with a shift in the lateral direction of the weight of theoperator seated on the boarding section, and also has a characteristicthat, while the mobile body is being stopped in the state where nodriving force is generated from the actuator, when the vehicle body isinclined in the roll direction, the inclination of the vehicle bodyfurther increases due to the gravitational force.

In the present specification, the “observed value” of a given statequantity related to the mobile body (such as the inclination angle inthe roll direction of the vehicle body) means a detected value of theactual value or an estimate of the state quantity. In this case, the“detected value” means an actual value of the state quantity which isdetected by an appropriate sensor. The “estimate” means a value which isestimated using a detected value of at least one state quantity havingcorrelation with the state quantity, on the basis of the correlation, orit means a pseudo estimate which can be considered to coincide with, oralmost coincide with, the actual value of the state quantity.

For the “pseudo estimate”, for example in the case where it is expectedthat the actual value of the state quantity can adequately track adesired value of the state quantity, the desired value may be adopted asthe pseudo estimate of the actual value of the state quantity.

Further, the “predetermined reference position with respect to thevehicle body” refers to the state where the center of gravity of theoperator is located on a plane of symmetry in the lateral direction ofthe vehicle body of the mobile body. Here, the “plane of symmetry in thelateral direction of the vehicle body” means the plane with respect towhich the vehicle body may be considered to be bilaterally symmetricalor almost bilaterally symmetrical. In other words, the “plane ofsymmetry” is a plane which agrees or almost agrees with a vertical plane(having its normal direction corresponding to the horizontal direction)that includes, in the state where the mobile body is standing on a flatground surface in a posture when traveling straight ahead, a centralpoint of a load applied from the contact ground surface to the frontwheel and a central point of a load applied from the contact groundsurface to the rear wheel of the mobile body.

Further, regarding the control input determining section, to “increasethe degree of displacement of the center of gravity of the operator”means to cause the center of gravity of the operator to be displacedrelatively with respect to the vehicle body toward the right side of thevehicle body when the center of gravity of the operator has beendisplaced from the predetermined reference position to the right side ofthe vehicle body, and it means to cause the center of gravity of theoperator to be displaced relatively with respect to the vehicle bodytoward the left side of the vehicle body when the center of gravity ofthe operator has been displaced from the predetermined referenceposition to the left side of the vehicle body.

Further, the “roll direction” means the direction about the axis in thelongitudinal direction of the vehicle body.

According to the first aspect of the invention, the control inputdetermining section determines the control input for controlling theactuator in accordance with the center-of-gravity displacement degreeindex value, in such a way as to increase the degree of displacement ofthe center of gravity of the operator indicated by the center-of-gravitydisplacement degree index value in the state where the center of gravityof the operator boarded on the boarding section is displaced from thepredetermined reference position.

Therefore, in the first aspect of the invention, the actuator iscontrolled such that, in the case where the center of gravity of theoperator is displaced from the predetermined reference position to alean-in or lean-out state by the operator's shift of his/her weight, amoment in the roll direction functioning to increase the degree of suchdisplacement will act on the vehicle body by the actuation of theactuator.

It is thus possible to quickly realize a lean-in or lean-out state whenthe operator shifts his/her weight in an attempt to achieve the lean-inor lean-out state.

In the first aspect of the invention, as the actuator, for example anactuator which steers a steered wheel, among the front and rear wheels,so as to cause a ground contact point of the steered wheel to movelaterally may be adopted (second aspect of the invention).

Alternatively, as the actuator, an actuator which moves a center ofgravity of the vehicle body so as to cause a moment in the rolldirection to act on the vehicle body by a gravitational force acting onthe vehicle body may be adopted (third aspect of the invention).

Alternatively, as the actuator, an actuator which causes the vehiclebody to swing in the roll direction with respect to the road surface maybe adopted (fourth aspect of the invention).

According to the second through fourth aspects of the invention, theactuator becomes the one which can cause a moment in the roll directionto appropriately act on the vehicle body.

It should be noted that the actuator in the first aspect of theinvention may have at least two functions among the function as theactuator in the second aspect of the invention, the function as theactuator in the third aspect of the invention, and the function as theactuator in the fourth aspect of the invention.

In the first through fourth aspects of the invention, it is preferablethat the control input determining section is configured to determinethe control input for controlling the actuator in such a way as toincrease the degree of displacement of the center of gravity of theoperator, on a condition that a magnitude of the degree of displacementof the center of gravity of the operator indicated by the determinedcenter-of-gravity displacement degree index value is a predeterminedvalue or greater (fifth aspect of the invention).

According to the fifth aspect of the invention, in the case where themagnitude of the degree of displacement of the center of gravity of theoperator is sufficiently small, it is possible to stop controlling theactuator to increase the degree of displacement of the center of gravityof the operator. This can prevent the actuator from being controlled toincrease the degree of displacement of the center of gravity of theoperator in a situation where it is highly likely that the operator doesnot want such control.

In the first through fifth aspects of the invention, the observed valueof the motional state used in the center-of-gravity displacement degreeindex value determining section includes, for example, an observed valueof an inclination state quantity representing a state of inclination ofthe vehicle body. In this case, it is preferable that thecenter-of-gravity displacement degree index value determining section isconfigured to sequentially determine the center-of-gravity displacementdegree index value, and also includes a section which calculates anestimate of the inclination state quantity through a dynamicscomputation using the determined center-of-gravity displacement degreeindex value, and is configured to update the center-of-gravitydisplacement degree index value based on a deviation between thecalculated value of the inclination state quantity and the observedvalue of the inclination state quantity (sixth aspect of the invention).

According to the sixth aspect of the invention, the center-of-gravitydisplacement degree index value determining section is configured as anobserver. Therefore, the center-of-gravity displacement degree indexvalue determining section can determine the center-of-gravitydisplacement degree index value to conform to the actual degree ofdisplacement of the center of gravity of the operator. Consequently, itis possible to improve the fllowability of the tilting of the vehiclebody according to the shift of the operator's weight.

In the sixth aspect of the invention, it may be possible to adopt, asthe dynamics computation carried out by the center-of-gravitydisplacement degree index value determining section, a dynamicscomputation based on a dynamic model which expresses dynamics of themobile body by, for example, dynamics of a mass point system formed ofan inverted pendulum mass point and a ground surface mass point, theinverted pendulum mass point moving in a horizontal direction above acontact ground surface of the mobile body comes into contact, inaccordance with a change of an inclination angle in the roll directionof the vehicle body and a change of a steering angle of the steeredwheel, the ground surface mass point moving horizontally on the contactground surface of the mobile body, in accordance with the change of thesteering angle of the steered wheel and independently of the change ofthe inclination angle in the roll direction of the vehicle body (seventhaspect of the invention).

It should be noted that the ground surface means the horizontal surfacewith which the front and rear wheels of the mobile body come intocontact.

According to the seventh aspect of the invention, it is possible toimprove the reliability of the estimate value of the inclination statequantity by the dynamics computation described above.

It should be noted that in the seventh aspect of the invention, a movingvelocity or the like of the inverted pendulum mass point, for example,may be adopted as the inclination state quantity.

Alternatively, in the sixth aspect of the invention, it may also bepossible to adopt, as the dynamics computation carried out by thecenter-of-gravity displacement degree index value determining section, adynamics computation based on a dynamic model which expresses dynamicsof the mobile body by, for example, dynamics of a system formed of amass point located at an overall center of gravity of the mobile bodyand inertia in a direction about an axis in the longitudinal directionof the mobile body (eighth aspect of the invention).

According to the eighth aspect of the invention, it is possible to makethe dynamics computation relatively simple.

It should be noted that in the eighth aspect of the invention, aninclination angular velocity in the roll direction of the vehicle body,for example, may be adopted as the inclination state quantity.

In the first through eighth aspects of the invention, the control inputdetermining section is preferably configured to determine the controlinput such that sensitivity of a change in the control input withrespect to a change in the center-of-gravity displacement degree indexvalue varies in accordance with a traveling speed of the mobile body(ninth aspect of the invention).

This makes it possible to determine the control input with sensitivitythat is appropriate for the traveling speed of the mobile body.

Further, in the fourth aspect of the invention in which the actuator isthe one which causes the vehicle body to swing in the roll directionwith respect to the road surface, it is preferable that the controldevice further includes a steering force estimating section whichestimates a steering force applied to a steered wheel, among the frontand rear wheels, as the operator boarded on the boarding sectionmanipulates a handle for steering the steered wheel, and that thecontrol input determining section is configured to determine the controlinput in accordance with the center-of-gravity displacement degree indexvalue and the estimated steering force (tenth aspect of the invention).

According to this configuration, the tilting in the roll direction ofthe vehicle body according to the shift of the operator's weight can beassisted appropriately by the driving force of the actuator. Inaddition, the vehicle body can be made to tilt to conform to thesteering force of the steered wheel that is intended by the operatorthrough manipulation of the handlebar.

It should be noted that the tenth aspect of the invention can becombined with any of the fifth through ninth aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing a schematic configuration of a mobile body(two-wheeled vehicle) in the first, second, third, or fourth embodimentof the present invention;

FIG. 2 is a plan view of a steering mechanism of the mobile body in FIG.1;

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2;

FIGS. 4A and 4B illustrate the operation of a second lock mechanism inthe steering mechanism shown in FIG. 2;

FIG. 5 is a block diagram showing the configuration related to thecontrol of the mobile body in FIG. 1;

FIG. 6 illustrates a two-mass-point model for use in control of a mobilebody:

FIGS. 7A, 7B, and 7C show the positional relationships of the centers ofgravity in the lean-with, lean-in, and lean-out states, respectively:

FIG. 8 is a block diagram showing the major functions of the controldevice in an embodiment;

FIG. 9 is a block and line diagram showing the processing performed bythe estimated inverted pendulum mass point lateral movement amountcalculating section shown in FIG. 8;

FIG. 10 is a block and line diagram showing the processing performed bythe estimated inverted pendulum mass point lateral velocity calculatingsection shown in FIG. 8;

FIG. 11 is a block and line diagram showing the processing performed bythe rider's center-of-gravity lateral displacement index valuecalculating section shown in FIG. 8;

FIG. 12 is a block and line diagram showing the processing performed bythe roll moment inertial force component calculating section shown inFIG. 11;

FIG. 13 is a block and line diagram showing the processing performed bythe roll moment floor reaction force component calculating section shownin FIG. 1:

FIG. 14 is a block and line diagram showing the processing performed bythe roll moment ground surface mass point component calculating sectionshown in FIG. 11;

FIG. 15 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 8;

FIG. 16 is a block and line diagram showing the processing performed bythe second steering angle command determining section shown in FIG. 8;

FIG. 17 is a block and line diagram showing the processing performed bythe desired traveling speed determining section shown in FIG. 8;

FIG. 18 is a block and line diagram showing the processing performed bya first steering actuator control section and a second steering actuatorcontrol section included in the control device in the first or secondembodiment:

FIG. 19 is a block and line diagram showing the processing performed bya front-wheel driving actuator control section included in the controldevice in the first or second embodiment:

FIG. 20 is a block diagram showing the major functions of the controldevice in the second embodiment;

FIG. 21 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 20:

FIG. 22 is a block and line diagram showing the processing performed bythe first steering angle command determining section shown in FIG. 20;

FIG. 23 is a block diagram showing the major functions of the controldevice in the third embodiment;

FIG. 24 is a block and line diagram showing the processing performed bythe rider's center-of-gravity lateral displacement index valuecalculating section shown in FIG. 23;

FIG. 25 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 23;

FIG. 26 is a block diagram showing the major functions of the controldevice in the fourth embodiment:

FIG. 27 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 26:

FIGS. 28A, 28B, and 28C are a front view, a side view, and a plan view,respectively, of a mobile body (three-wheeled vehicle) in the fifth orsixth embodiment of the present invention:

FIG. 29A and FIG. 29B show the mobile body in which FIG. 29A shows theleaned state of the vehicle body of the mobile body in the fifth orsixth embodiment and FIG. 29B shows the steered state of the frontwheels of that mobile body;

FIG. 30 is a block diagram showing the configuration related to thecontrol of the mobile body in the fifth or sixth embodiment;

FIG. 31 is a block diagram showing the major functions of the controldevice in the fifth embodiment:

FIG. 32 is a block and line diagram showing the processing performed bythe estimated inverted pendulum mass point lateral movement amountcalculating section shown in FIG. 31;

FIG. 33 is a block and line diagram showing the processing performed bythe rider's center-of-gravity lateral displacement index valuecalculating section shown in FIG. 31;

FIG. 34 is a block and line diagram showing the processing performed bythe roll moment inertial force component calculating section shown inFIG. 33;

FIG. 35 is a block and line diagram showing the processing performed bythe roll moment floor reaction force component calculating section shownin FIG. 33;

FIG. 36 is a block and line diagram showing the processing performed bythe roll moment ground surface mass point component calculating sectionshown in FIG. 33:

FIG. 37 is a block and line diagram showing the processing performed bythe rider-steering-based roll manipulated variable calculating sectionshown in FIG. 31;

FIG. 38 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 31;

FIG. 39 is a block diagram showing the major functions of the controldevice in the sixth embodiment:

FIG. 40 is a block and line diagram showing the processing performed bythe rider's center-of-gravity lateral displacement index valuecalculating section shown in FIG. 39;

FIG. 41 is a block and line diagram showing the processing performed bythe rider-steering-based roll manipulated variable calculating sectionshown in FIG. 39;

FIG. 42 is a block and line diagram showing the processing performed bythe posture control arithmetic section shown in FIG. 39:

FIGS. 43A, 43B, and 43C are a back view, a side view, and a plan view,respectively, of another exemplary mobile body (four-wheeled vehicle) towhich the present invention is applicable:

FIG. 44 is a side view of yet another exemplary mobile body(three-wheeled vehicle) to which the present invention is applicable;and

FIG. 45 is a perspective view showing the configuration of a rolldriving mechanism included in the mobile body in FIG. 44.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described below withreference to FIGS. 1 to 19.

Referring to FIG. 1, a mobile body (mobile vehicle) 1 of the presentembodiment is a straddle-ridden two-wheeled vehicle which includes avehicle body 2, and a front wheel 3 f and a rear wheel 3 r arrangedspaced apart from each other in the longitudinal direction of thevehicle body 2. Hereinafter, the mobile body 1 will be referred to as“two-wheeled vehicle 1”.

The vehicle body 2 is provided with a boarding section 4 for an operator(rider). In the present embodiment, the boarding section 4 is a seat forthe operator (rider) to sit astride.

At the front portion of the vehicle body 2, a front-wheel supportmechanism 5 for pivotally supporting the front wheel 3 f is mountedthrough the intermediary of a steering mechanism 6. The front wheel 3 fis pivotally supported by the front-wheel support mechanism 5, viabearings or the like, such that the front wheel 3 f can rotate about itsaxle centerline (rotational axis of the front wheel 3 f).

As the front-wheel support mechanism 5, one having the structure similarto that of the front-wheel support mechanism of a typical motorcycle,for example, may be adopted. The front-wheel support mechanism 5illustrated in the figure has a front fork 22 which includes a damper(not shown), for example. The front wheel 3 f is pivotally supported atthe lower end of the front fork 22.

In the present embodiment, a front-wheel driving actuator 7 forrotatively driving the front wheel 3 f about its axle centerline isattached to the axle of the front wheel 3 f. The front-wheel drivingactuator 7 has the function as a power engine which generates a thrustforce for the two-wheeled vehicle 1. In the present embodiment, thefront-wheel driving actuator 7 is made up, for example, of an electricmotor (with a speed reducer).

Supplementally, the front-wheel driving actuator 7 may be a hydraulicactuator, for example, instead of the electric motor, or it may be madeup of an internal combustion engine. Further, the front-wheel drivingactuator 7 may be mounted to the vehicle body 2 at a position apart fromthe axle of the front wheel 3 f, and the front-wheel driving actuator 7and the axle of the front wheel 3 f may be connected by an appropriatepower transmission device.

At the rear portion of the vehicle body 2, a rear-wheel supportmechanism 8 for pivotally supporting the rear wheel 3 r is mounted. Therear wheel 3 r is pivotally supported by the rear-wheel supportmechanism 8, via bearings or the like, such that the rear wheel 3 r canrotate about its axle centerline (rotational axis of the rear wheel 3r).

As the rear-wheel support mechanism 8, one having the structure similarto that of the rear-wheel support mechanism of a typical motorcycle(such as a suspension mechanism including a swing arm, coil spring,damper, and so on), for example, may be adopted. In FIG. 1, therear-wheel support mechanism 8 is simplified and shown schematically.

Supplementally, the front-wheel support mechanism 5 and the rear-wheelsupport mechanism 8 are not limited to those of a typical motorcycle;those with various kinds of structures may be adopted.

The steering mechanism 6 interposed between the vehicle body 2 and thefront-wheel support mechanism 5 is a mechanism for steering the frontwheel 3 f which is a steered wheel of the two-wheeled vehicle 1. Itshould be noted that FIG. 1 shows only the main configuration of thesteering mechanism 6.

In the present embodiment, the steering mechanism 6 (the specificstructure of which will be described later) is configured to have twosteering axes of a first steering axis Cf1 and a second steering axisCf2 as the steering axes of the front wheel 3 f (rotational axes forsteering the front wheel 3 f). The front-wheel support mechanism 5 isrotatable, together with the front wheel 3 f, about the respective axesof the first steering axis Cf1 and the second steering axis Cf2. Thefront wheel 3 f is steered through such rotation.

The first steering axis Cf1 and the second steering axis Cf2 arearranged such that they are tilted backward in a basic posture state(posture state shown in FIG. 1) of the two-wheeled vehicle 1, and suchthat a trail t1 based on the first steering axis Cf1 is smaller than atrail t2 based on the second steering axis Cf2 and, of the trails t1 andt2, at least the trail t1 based on the first steering axis Cf1 takes avalue equal to or less than a predetermined positive value.

Further, in the present embodiment, the first steering axis Cf1 and thesecond steering axis Cf2 are parallel to each other in the basic posturestate of the two-wheeled vehicle 1. Accordingly, the inclination angles(on the acute side) of the first steering axis Cf1 and the secondsteering axis Cf2 with respect to the vertical direction, or, the casterangles θcs are set to be the same as each other.

The basic posture state of the two-wheeled vehicle 1 is, as shown inFIG. 1, the state in which the two-wheeled vehicle 1 is stationary in astraight-ahead posture (posture when traveling straight ahead) on a flatcontact ground surface S. More specifically, the basic posture state isthe state in which the front wheel 3 f and the rear wheel 3 r arestanding still in the upright posture on the flat contact ground surfaceS and in which the axle centerlines of the front wheel 3 f and the rearwheel 3 r extend in parallel with each other in the horizontal directionorthogonal to the longitudinal direction of the vehicle body 2.

The steering axis (first steering axis Cf1 or second steering axis Cf2)being tilted backward means that the steering axis extends obliquelywith respect to the vertical direction and the horizontal direction suchthat the steering axis has its upper portion located rearward relativeto its lower portion. In the description of the present embodiment, thecaster angle based on such a steering axis tilted backward is defined asa positive angle. Therefore, the caster angles θcs based on the firststeering axis Cf1 and the second steering axis Cf2 are positive angles.

Further, the trail t1 based on the first steering axis Cf1 is a distancefrom a ground contact point P1 of the front wheel 3 f of the two-wheeledvehicle 1 in the basic posture state (specifically, the point ofintersection of a vertical line passing through the center point of theaxle of the front wheel 3 f and the contact contact ground surface S) tothe point of intersection P2 of the first steering axis Cf1 and thecontact contact ground surface S. The trail t2 based on the secondsteering axis Cf2 is a distance from the ground contact point P1 of thefront wheel 3 f to the point of intersection P3 of the second steeringaxis Cf2 and the contact contact ground surface S.

In this case, in the description of the present embodiment, in terms ofpolarity of the trail (t1 or t2) based on each steering axis (firststeering axis Cf1 or second steering axis Cf2), the trail in the casewhere the point of intersection (P2 or P3) of the steering axis and thecontact contact ground surface S is positioned in front of the groundcontact point P1 of the front wheel 3 f is defined as a positive value,and the trail in the case where the point of intersection (P2 or P3) ofthe steering axis and the contact contact ground surface S is positionedbehind the ground contact point P1 of the front wheel 3 f is defined asa negative value.

In the present embodiment, as shown in FIG. 1 for example, the firststeering axis Cf1 and the second steering axis Cf2 are arranged suchthat the trail t1 based on the first steering axis Cf1 takes a negativevalue and the trail t2 based on the second steering axis Cf2 takes apositive value (such that t1<0<t2).

It has been found through the studies conducted by the present inventorsand others that, in the case of controlling the posture (inclinationangle) in the roll direction of the vehicle body 2 to a desired postureby steering the front wheel 3 f, it is preferable that the trail basedon a steering axis of the front wheel 3 f take a value equal to orsmaller than a predetermined positive value in order to effectivelyproduce a force (moment) for restoring the posture in the roll directionof the vehicle body 2 according to the steering of the front wheel 3 f.

For this reason, in the present embodiment, the trail t1 based on thefirst steering axis Cf1 is set to a negative value, as described above.

The predetermined positive value for the trail is a value which isdetermined in accordance with, for example, the height of the center ofgravity of the two-wheeled vehicle 1, the mass of the two-wheeledvehicle 1, the moment of inertia about an axis in the longitudinaldirection passing through the center of gravity of the two-wheeledvehicle 1, the horizontal distances from the center of gravity to thefront wheel 3 f and to the rear wheel 3 r, and the radii of curvature ofthe cross sections of the front wheel 3 f and the rear wheel 3 r. Thepredetermined value is described in detail in, for example, JapanesePatent Applications Laid-Open Nos. 2014-091386 and 2014-091385.Therefore, the detailed description of the predetermined value will beomitted herein.

It should be noted that the trail t1 based on the first steering axisCf1 may be set to a positive value of not larger than the predeterminedvalue, or to zero.

An example of the specific configuration of the steering mechanism 6will now be described with reference to FIGS. 2 and 3. As shown in FIGS.2 and 3, the steering mechanism 6 has a steering shaft plate 13 which ispivotally supported, via a first steering shaft 17, so as to berotatable with respect to the vehicle body 2, and the front-wheelsupport mechanism 5 is pivotally supported, via a second steering shaft21, so as to be rotatable with respect to this steering shaft plate 13.

The first steering shaft 17 is supported in a freely rotatable manner bya housing 16 secured to the vehicle body 2. Specifically, the firststeering shaft 17 penetrates from an upper side to a lower side of thehousing 16, through its inner space. The first steering shaft 17 isfreely rotatably supported by the housing 16, via bearings or the like,at its portions penetrating the upper side and the lower side of thehousing 16. The center axis (rotational axis) of this first steeringshaft corresponds to the aforesaid first steering axis Cf1.

The steering shaft plate 13 is made up of an upper plate 18 and a lowerplate 19 which extend in the direction perpendicular to the firststeering shaft 17, and a coupling plate 20 which couples the upper plate18 with the lower plate 19. The upper plate 18, the lower plate 19, andthe coupling plate 20 have their plate surfaces parallel to the lateraldirection of the vehicle body 2. The cross sections of the platesperpendicular to the lateral direction form an H shape, as shown in FIG.3.

The end portions of the first steering shaft 17 projecting upward anddownward from the housing 16 are secured to the rear end portions of theupper plate 18 and the lower plate 19, respectively. In this manner, thesteering shaft plate 13 is supported via the housing 16 and the firststeering shaft 17, so as to be rotatable about the center axis (firststeering axis Cf1) of the first steering shaft 17, with respect to thevehicle body 2.

The second steering shaft 21 is freely rotatably supported by the frontend portions of the upper plate 18 and the lower plate 19 via bearingsor the like. The second steering shaft 21 extends from the upper side ofthe upper plate 18 to the lower side of the lower plate 19. The centeraxis (rotational axis) of this second steering shaft 21 corresponds tothe aforesaid second steering axis Cf2.

At the upper portion of the front fork 22 of the front-wheel supportmechanism 5, a top bridge 23 and a bottom bridge 24 are provided, withtheir front side portions secured to the front fork 22. The end portionsof the second steering shaft 21 projecting upward from the upper plate18 and downward from the lower plate 19 are secured to the rear sideportions of the top bridge 23 and the bottom bridge 24, respectively.

With this configuration, the front-wheel support mechanism 5 and thefront wheel 3 f are supported via the second steering shaft 21, so as tobe rotatable about the center axis (second steering axis Cf2) of thesecond steering shaft 21, with respect to the steering shaft plate 13.

Further, the front-wheel support mechanism 5 and the front wheel 3 f arerotatable about the first steering axis Cf1 through the rotation of thesteering shaft plate 13 (about the first steering axis Cf1) with respectto the vehicle body 2.

The steering mechanism 6 further includes, inside the housing 16: afirst steering actuator 15 which rotatively drives the steering shaftplate 13 about the first steering axis Cf1; a first lock mechanism 27which is switchable between a locked state, in which the steering shaftplate 13 is fixed to the vehicle body 2, and an unlocked state, in whichthe fixing is released, and a second lock mechanism 28 which isswitchable between a locked state, in which the steering shaft plate 13is fixed to the vehicle body 2 in a neutral position of the steeringshaft plate 13, and an unlocked state, in which the fixing is released.

It should be noted that the neutral position of the steering shaft plate13 corresponds to the rotational position of the steering shaft plate 13in the aforesaid basic posture state of the two-wheeled vehicle 1 (or anon-steered state of the front wheel 3 f).

In the present embodiment, the first steering actuator 15 is made up,for example, of an electric motor. The first steering actuator 15transmits a rotative driving force to the first steering shaft 17 via afirst pinion 25, which is secured to an output shaft of the firststeering actuator 15, and a first gear 26, which is engaged with thefirst pinion 25 and secured to the first steering shaft 17.

It should be noted that the first steering actuator 15 may be made up ofa hydraulic actuator.

The first lock mechanism 27 includes: a brake disc 29 which is securedperpendicularly to the first steering shaft 17, a brake pad 30 which issupported so as to be movable between an engaged position where it isengaged with the brake disc 29 and a disengaged position where theengagement is released, a coil spring 31 which urges the brake pad 30toward the engaged position, and an electromagnet 32 which causes thebrake pad 30 to move to the disengaged position against the biasingforce of the coil spring 31.

In this first lock mechanism 27, when the electromagnet 32 is notenergized, the brake pad 30 is placed in the engaged position by thecoil spring 31. At this time, the brake pad 30 is engaged with the brakedisc 29, so the first lock mechanism 27 attains the locked state.

When the electromagnet 32 is energized, the brake pad 30 moves to thedisengaged position against the biasing force of the coil spring 31. Atthis time, the brake pad 30 is disengaged from the brake disc 29, so thefirst lock mechanism 27 attains the unlocked state.

In the present embodiment, the brake disc 29 also has the function as acam. The second lock mechanism 28 includes: the brake disc 29 serving asa cam, a roller 33 which rolls along a cam face on the outer peripheryof the brake disc 29, an iron core 34 which pivotally supports theroller 33 in a freely rotatable manner and which is guided movably inthe direction orthogonal to the first steering shaft 17, a coil spring35 which urges the iron core 34 in the direction in which the roller 33pushes the cam face, and an electromagnet 36 for attracting the ironcore 34 in the direction opposite to the biasing force applied by thecoil spring 35.

The operations of the second lock mechanism 28 will be described withreference to FIGS. 4A and 4B. In FIG. 4A, the two-dot chain line showsthe upper plate 18 and the lower plate 19 in the state where thesteering shaft plate 13 is in the neutral position. In FIG. 4B, thetwo-dot chain line shows the upper plate 18 and the lower plate 19 whenthe steering shaft plate 13 has been rotated from the neutral position.

As shown in FIGS. 4A and 4B, the brake disc 29 comprises a heart-shapedplate cam. The second lock mechanism 28 is configured such that, whenthe steering shaft plate 13 is in the neutral position, the roller 33 ispositioned in the dent of the heart-shaped cam face of the brake disc29, as shown in FIG. 4A.

When the electromagnet 36 is not energized, the roller 33 at the tip endof the iron core 34 is pressed against the cam face of the brake disc 29by the biasing force of the coil spring 35. As a result, the steeringshaft plate 13 is urged toward the neutral position and is maintained inthe neutral position. This state corresponds to the locked state of thesecond lock mechanism 28.

From this locked state, when the steering shaft plate 13 is rotated asshown in FIG. 4B, the iron core 34 is moved in the direction away fromthe first steering shaft 17 by the cam face of the brake disc 29 via theroller 33. At this time, the electromagnet 36 is energized forpermitting such a movement. With this energization, the iron core 34 isattracted against the biasing force of the coil spring 35. As a result,the biasing force for making the steering shaft plate 13 return to theneutral position is reduced or cancelled. This state corresponds to theunlocked state of the second lock mechanism 28.

For causing the steering shaft plate 13 to return to the neutralposition, the energization of the electromagnet 36 is stopped. Thebiasing force of the coil spring 35 is transmitted again to the cam faceof the brake disc 29. As a result, the steering shaft plate 13 is urgedtoward the neutral position and is held in the neutral position.

Returning to FIGS. 2 and 3, the steering mechanism 6 further includes: asecond steering actuator 37 which rotatively drives the front-wheelsupport mechanism 5 about the second steering axis Cf2, and a clutchmechanism 38 which is switchable between a transmission-enabled state inwhich the driving force of the second steering actuator 37 istransmitted to the second steering shaft 21, and atransmission-interrupted state in which the transmission is interrupted.The second steering actuator 37 and the clutch mechanism 38 are arrangedat the front side of the steering shaft plate 13, between the upperplate 18 and the lower plate 19.

In the present embodiment, the second steering actuator 37 is made up,for example, of an electric motor. The second steering actuator 37transmits the rotative driving force to the second steering shaft 21,via a pinion 39 secured to an output shaft of the second steeringactuator 37, a gear 40 supported freely rotatably on the second steeringshaft 21, and the clutch mechanism 38 in turn.

It should be noted that the second steering actuator 37 may be made upof a hydraulic actuator.

The clutch mechanism 38 includes: a clutch plate 41 which is secured tothe gear 40, a clutch plate 42 which is secured to the second steeringshaft 21, an iron core 43 of a cylindrical shape which is fitted ontothe second steering shaft 21 so as to be movable along the secondsteering shaft 21, a coil spring 44 which urges the iron core 43 in thedirection (transmission-interrupting direction) of separating the clutchplate 42 from the clutch plate 41, and an electromagnet 45 which movesthe iron core 43 against the biasing force of the coil spring 44 so asto bring the clutch plate 42 into pressure contact with the clutch plate41.

In this clutch mechanism 38, when the electromagnet 45 is not energized,the clutch plate 42 is separated from the clutch plate 41 by the biasingforce of the coil spring 44. In this state, the rotative driving forceis not transmitted from the second steering actuator 37 to the secondsteering shaft 21. This state corresponds to thetransmission-interrupted state of the clutch mechanism 38.

When the electromagnet 45 is energized, the clutch plates 42 and 41 arein pressure contact with each other against the biasing force of thecoil spring 44. In this state, the rotative driving force is transmittedfrom the second steering actuator 37 to the second steering shaft 21 viathe clutch plates 42 and 41. This state corresponds to thetransmission-enabled state of the clutch mechanism 38.

The steering mechanism 6 further includes a handlebar 46 used by anoperator of the two-wheeled vehicle 1 for steering the front wheel 3 f,and a handlebar link mechanism 47 which couples the handlebar 46 withthe front-wheel support mechanism 5.

The handlebar 46 extends generally in the vehicle width direction of thetwo-wheeled vehicle 1. The handlebar 46 has its central portion securedto a handlebar shaft 53 which is pivotally supported in a freelyrotatable manner via a bearing 52 on the upper plate 18 of the steeringshaft plate 13. In the present embodiment, the handlebar shaft 53 isarranged such that the handlebar axis as its center axis is collinearwith the first steering axis Cf1.

Although not shown in detail in the figure, this handlebar 46 isequipped with an accelerator grip, brake lever, turn signal switch, andso on, as with the handlebar of a typical motorcycle.

The handlebar link mechanism 47 is operable, in response to amanipulation of rotating the handlebar 46 about the handlebar axis, totransmit the rotative manipulation of the handlebar 46 to thefront-wheel support mechanism 5 so as to cause the front-wheel supportmechanism 5 to rotate about the second steering axis Cf2.

Specifically, the handlebar link mechanism 47 includes: a first lever 48which is coupled to the handlebar shaft 53 so as to rotate about thehandlebar axis in an integrated manner with the handlebar 46, a secondlever 49 which is attached to the top bridge 23 so as to rotate aboutthe second steering axis C12 in an integrated manner with the top bridge23, and a link 50 which couples the first lever 48 with the second lever49.

The link 50 extends in the direction orthogonal to the second steeringaxis Cf2. The link 50 is pivotally supported so as to be freelyswingable about axes parallel to the first steering axis Cf1 withrespect to the first lever 48 and the second lever 49. It is configuredsuch that the joint between the link 50 and the first lever 48 and thejoint between the link 50 and the second lever 49 have a certaindistance from the handlebar axis (first steering axis Cf1) and thesecond steering axis Cf2, respectively.

With the handlebar link mechanism 47 configured as described above, whenthe handlebar 46 is rotatively manipulated about the handlebar axis, arotative force about the second steering axis Cf2 is applied to thefront-wheel support mechanism 5 via the handlebar link mechanism 47.This enables the steering of the front wheel 3 f according to therotative manipulation of the handlebar 46.

In the two-wheeled vehicle 1 configured as described above, steering thefront wheel 3 f about the first steering axis Cf1 or the second steeringaxis Cf2 can cause a moment in the roll direction to act on the vehiclebody 2.

The two-wheeled vehicle 1 of the present embodiment further includes theconfiguration shown in FIG. 5 as the configuration for operationcontrol.

Specifically, as shown in FIG. 5, the two-wheeled vehicle 1 includes acontrol device 60 which carries out control processing for controllingthe operations of the aforesaid first steering actuator 15, secondsteering actuator 37, and front-wheel driving actuator 7.

The two-wheeled vehicle 1 further includes, as sensors for detectingvarious kinds of state quantities necessary for the control processingin the control device 60, a vehicle-body inclination detector 61 fordetecting an inclination angle in the roll direction of the vehicle body2, a first steering angle detector 62 for detecting a first steeringangle which is the steering angle (rotational angle) of the front wheel3 f about the first steering axis Cf1, a second steering angle detector63 for detecting a second steering angle which is the steering angle(rotational angle) of the front wheel 3 f about the second steering axisCf2, a handlebar torque detector 64 for detecting a handlebar torquewhich is the steering force of the front wheel 3 f (rotative drivingforce about the second steering axis Cf2) applied via the handlebar 46by an operator, a front-wheel rotational speed detector 65 for detectinga rotational speed (angular velocity) of the front wheel 3 f, and anaccelerator manipulation detector 66 for detecting an acceleratormanipulated variable which is the manipulated variable (rotationalamount) of the accelerator grip of the handlebar 46. It should be notedthat illustration of these detectors 61 to 66 is omitted in FIGS. 1 to4.

The control device 60 is an electronic circuit unit made up of a CPU,RAM, ROM, interface circuit, and so on. The control device 60 is mountedon an appropriate portion of the vehicle body 2. The control device 60receives outputs (detection signals) from the respective detectors 61 to66 described above.

The control device 60 may be made up of a plurality of mutuallycommunicable electronic circuit units. In this case, the electroniccircuit units constituting the control device 60 may be disposed inplaces distant from one another.

The vehicle-body inclination detector 61 is made up of an accelerationsensor and a gyro sensor (angular velocity sensor), for example. Thevehicle-body inclination detector 61 is mounted on an appropriateportion of the vehicle body 2. In this case, the control device 60carries out predetermined measurement and computation processing, suchas computation by a strapdown system, on the basis of the outputs fromthe acceleration sensor and the gyro sensor, to thereby measure theinclination angle in the roll direction (more specifically, inclinationangle in the roll direction with respect to the vertical direction(direction of gravitational force)) of the vehicle body 2.

In the description of the present embodiment, the inclination angle inthe roll direction of the vehicle body 2 in the basic posture state ofthe two-wheeled vehicle 1 is zero. The positive direction of theinclination angle in the roll direction corresponds to the directionthat makes the vehicle body 2 lean to the right (in the clockwisedirection) as the two-wheeled vehicle 1 is seen from behind.

The first steering angle detector 62 and the second steering angledetector 63 are each made up, for example, of a rotary encoder or apotentiometer. In this case, the first steering angle detector 62 isattached to the first steering shaft 17 or the first steering actuator15, for example, so as to output a signal corresponding to the rotationof the first steering shaft 17. Similarly, the second steering angledetector 63 is attached to the second steering shaft 21 or the secondsteering actuator 37, for example, so as to output a signalcorresponding to the rotation of the second steering shaft 21.

In the description of the present embodiment, the first and secondsteering angles of the front wheel 3 f are both zero in the basicposture state of the two-wheeled vehicle 1 when the front wheel 3 f isin a non-steered state. The positive direction of the first steeringangle corresponds to the direction that makes the front wheel 3 f rotatecounterclockwise about the first steering axis Cf1 as the two-wheeledvehicle 1 is seen from above. The positive direction of the secondsteering angle corresponds to the direction that makes the front wheel 3f rotate counterclockwise about the second steering axis Cf2 as thetwo-wheeled vehicle 1 is seen from above.

The handlebar torque detector 64 is made up, for example, of a forcesensor or a torque sensor disposed in a power transmission systembetween the handlebar 46 and the second steering shaft 21 so as tooutput a signal corresponding to the handlebar torque that is appliedfrom the handlebar 46 side to the second steering shaft 21.

In the description of the present embodiment, the positive direction ofthe handlebar torque corresponds to the direction that makes the frontwheel 3 f rotate counterclockwise about the first steering axis Cf1 asthe two-wheeled vehicle 1 is seen from above.

The front-wheel rotational speed detector 65 is made up, for example, ofa rotary encoder attached to the axle of the front wheel 3 f so as tooutput a signal corresponding to the rotational speed of the front wheel3 f.

The accelerator manipulation detector 66 is made up, for example, of arotary encoder or a potentiometer built in the handlebar 46 so as tooutput a signal corresponding to the manipulated variable (rotationalamount) of the accelerator grip.

The functions of the above-described control device 60 will be describedfurther below. In the following description, an XYZ coordinate system,shown in FIG. 1, is used. This XYZ coordinate system is a coordinatesystem in which, in the basic posture state of the two-wheeled vehicle1, the vertical direction (up-and-down direction) is defined as theZ-axis direction, the longitudinal direction (front-back direction) ofthe vehicle body 2 as the X-axis direction, the lateral direction(right-left direction) of the vehicle body 2 as the Y-axis direction,and a point on the contact ground surface S immediately beneath theoverall center of gravity G of the two-wheeled vehicle 1 as the origin.The positive directions of the X, Y, and Z axes are frontward, leftward,and upward, respectively.

In the present embodiment, for controlling the posture (inclinationangle) in the roll direction of the two-wheeled vehicle 1, atwo-mass-point model is used which describes the dynamic behavior of thetwo-wheeled vehicle 1 (behavior related to the inclination in the rolldirection of the vehicle body 2) using two mass points. Thetwo-mass-point model is described in detail by the present applicant in,for example, Japanese Patent Applications Laid-Open Nos. 2014-091386 and2014-091385. Therefore, in the present embodiment, the two-mass-pointmodel will be described only in brief.

As shown in FIG. 6, the two-mass-point model is made up of a mass point71, which moves horizontally in the Y-axis direction above a contactground surface S with which the two-wheeled vehicle 1 comes intocontact, in accordance with the inclination angle ϕb in the rolldirection of the vehicle body 2 and the steering of the front wheel 3 f,and a mass point on the ground surface (or, a “ground surface masspoint”) 72, which moves horizontally in the Y-axis direction on thecontact ground surface S in accordance with the steering of the frontwheel 3 f and independently of the inclination angle ϕb in the rolldirection of the vehicle body 2. The mass point 71 exhibits a behaviorsimilar to that of the mass point of an inverted pendulum, and it ishereinafter called the inverted pendulum mass point 71.

In this case, the mass m1 and the height h′ of the inverted pendulummass point 71 and the mass m2 of the ground surface mass point 72 areset to satisfy (or almost satisfy) the relationships expressed by thefollowing expressions (1a) to (1c). In the description of the presentembodiment, “*” is a sign representing multiplication.m1+m2=m  (1a)m1*c=m2*h  (1b)m1*c*c+m2*h*h=I  (1c)where c≡h′−h  (1d)Here, m represents the overall mass of the two-wheeled vehicle 1, hrepresents the height of the overall center of gravity G of thetwo-wheeled vehicle 1, and I represents the moment of inertia in theroll direction of the two-wheeled vehicle 1.

The overall mass m of the two-wheeled vehicle 1 is, more specifically, atotal of the mass of the two-wheeled vehicle 1 alone and the mass of theoperator riding on the two-wheeled vehicle 1. The overall center ofgravity G of the two-wheeled vehicle 1 is the center of gravity of thetotal of the two-wheeled vehicle 1 and the operator riding thereon. Themoment of inertia I in the roll direction of the two-wheeled vehicle 1is the moment of inertia about an axis in the longitudinal direction(parallel to the X axis) that passes through the overall center ofgravity G of the two-wheeled vehicle 1.

In the two-mass-point model described above, in the basic posture stateof the two-wheeled vehicle 1, the inverted pendulum mass point 71 andthe ground surface mass point 72 are on a vertical line passing throughthe overall center of gravity G (i.e. on the Z axis), in a position atthe height h′ from the contact ground surface S and in a position on thecontact ground surface S (position where the height from the contactground surface S is zero), respectively. The inverted pendulum masspoint 71 and the ground surface mass point 72 are on the plane ofsymmetry of the vehicle body 2.

Here, the plane of symmetry of the vehicle body 2 is a plane withrespect to which the vehicle body 2 may be considered to be bilaterallysymmetrical or almost bilaterally symmetrical. In other words, the planeof symmetry is a plane which agrees or almost agrees with a verticalplane (having its normal direction corresponding to the horizontaldirection) that includes, in the state where the two-wheeled vehicle 1(mobile body) is standing on a flat ground surface in a posture whentraveling straight ahead, a central point of a load applied from thecontact ground surface to the front wheel 3 f and a central point of aload applied from the contact ground surface to the rear wheel 3 r ofthe two-wheeled vehicle 1 (mobile body). The same applies to the planeof symmetry of the vehicle body of a mobile body in any of the secondthrough sixth embodiments described below.

The inverted pendulum mass point 71 moves in the lateral direction(Y-axis direction) at the height h′, in accordance with the change ininclination angle ϕb in the roll direction of the vehicle body 2 and thesteering of the front wheel 3 f (change in first steering angle δf1 orsecond steering angle δf2) from the basic posture state. The groundsurface mass point 72 moves in the lateral direction (Y-axis direction)on the contact ground surface S, in accordance with the steering of thefront wheel 3 f (change in first steering angle δf1 or second steeringangle δf2) from the basic posture state.

In the case where the position of the center of gravity of the operatorof the two-wheeled vehicle 1 is maintained on the plane of symmetry ofthe vehicle body 2, the positions of the inverted pendulum mass point 71and the ground surface mass point 72 are held on the plane of symmetryof the vehicle body 2. In this case, the inclination angle in the rolldirection of the line segment connecting the inverted pendulum masspoint 71 and the ground surface mass point 72 agrees with theinclination angle ϕb in the roll direction of the vehicle body 2.

Further, the dynamic behavior of the inverted pendulum mass point 71 inthe two-mass-point model is similar to that of the mass point of theinverted pendulum. Specifically, the equation of motion (dynamic model)of the inverted pendulum mass point 71 is expressed by the followingexpression (2).m1*h′*Pb_diff_dot2_y=m1*g*Pb_diff_y−Mp−M2−Mi  (2)

Here, Pb_diff_y represents the movement amount in the Y-axis direction(hereinafter, referred to as “inverted pendulum mass point lateralmovement amount”) of the inverted pendulum mass point 71 from theposition in the basic posture state of the two-wheeled vehicle 1,Pb_diff_dot2_y represents a second order differential of the invertedpendulum mass point lateral movement amount Pb_diff_y (i.e. theacceleration in the Y-axis direction of the inverted pendulum mass point71), and g represents a gravitational acceleration constant.

Further, with the point of action on the contact ground surface S of aresultant force of reaction forces in the vertical direction which acton the front wheel 3 f and the rear wheel 3 r from the contact groundsurface S being defined as the center point of contact pressure which isCOP, Mp represents a moment (hereinafter, referred to as “roll momentfloor reaction force component”) which is produced in the roll directionabout the origin of the XYZ coordinate system according to thatresultant force (=m*g) acting on the COP. M2 represents a moment(hereinafter, referred to as “roll moment ground surface mass pointcomponent”) which is produced in the roll direction about the origin ofthe XYZ coordinate system according to the gravitational force (=m2*g)acting on the ground surface mass point 72. Mi represents a moment(hereinafter, referred to as “roll moment inertial force component”)which is produced in the roll direction about the origin of the XYZcoordinate system according to the inertial force accompanying themotion of the two-wheeled vehicle 1.

In the description of the present embodiment, the positive directions ofMp. M2, and Mi are the clockwise direction (direction making the vehiclebody 2 lean to the right) when the two-wheeled vehicle 1 is seen frombehind (toward the front of the vehicle body 2).

When the amount of movement of the ground surface mass point 72 in theY-axis direction from the position (at the origin of the XYZ coordinatesystem) in the basis posture state of the two-wheeled vehicle 1 isdenoted as q, the roll moment ground surface mass point component M2 iscalculated by the following expression (3).M2=−m2*g*q  (3)

It should be noted that when the first steering angle δf1 and the secondsteering angle δf2 are relatively small in magnitude (close to zero),the movement amount q in the Y-axis direction of the ground surface masspoint 72 can be obtained approximately by, for example, the followingexpression (4).q=(a1*sin(θcs)*(δf1)+a2*sin(θcs)*(δf1+δf2))*(Lr/L)  (4)

Here, a1 represents the height (from the contact ground surface S) ofthe point of intersection between the first steering axis Cf1 and avertical line passing through the center of the axle of the front wheel3 f of the two-wheeled vehicle 1 in the basic posture state, a2represents the height (from the contact ground surface S) of the pointof intersection between the second steering axis Cf2 and the verticalline passing through the center of the axle of the front wheel 3 f ofthe two-wheeled vehicle 1 in the basic posture state, Lr represents thedistance in the longitudinal direction (X-axis direction) between theground contact point of the rear wheel 3 r and the overall center ofgravity G of the two-wheeled vehicle 1 in the basic posture state, and Lrepresents the distance in the longitudinal direction (X-axis direction)between the ground contact point of the front wheel 3 f and the groundcontact point of the rear wheel 3 r of the two-wheeled vehicle 1 in thebasic posture state.

Further, when the amount of movement in the Y-axis direction from theposition (the origin position of the XYZ coordinate system) of the COPin the basic posture state of the two-wheeled vehicle 1 is denoted as p,the roll moment floor reaction force component Mp is calculated by thefollowing expression (5).Mp=m*g*p  (5)

It should be noted that when the first steering angle δf1 and the secondsteering angle δf2 are relatively small in magnitude (close to zero),the movement amount p in the Y-axis direction of the COP can be obtainedapproximately by the following expression (6), for example, using qobtained by the above expression (4).p=(Lr/L)*(Rf*sin(θcs)*(δf1+δf2))−q*Rg/h′  (6)whereRg≡(Lr/L)*Rr+(Lr/L)*Rf  (7)

Here, Rf represents the radius of curvature of the transversecross-sectional shape of the ground contact part of the front wheel 3 fas seen in a cross section (orthogonal to the X-axis direction)including the center of axle and the ground contact point of the frontwheel 3 f of the two-wheeled vehicle 1 in the basic posture state. Rrrepresents the radius of curvature of the transverse cross-sectionalshape of the ground contact part of the rear wheel 3 r as seen in across section (orthogonal to the X-axis direction) including the centerof axle and the ground contact point of the rear wheel 3 r of thetwo-wheeled vehicle 1 in the basic posture state. Lf represents thedistance in the longitudinal direction (X-axis direction) between theground contact point of the front wheel 3 f and the overall center ofgravity G of the two-wheeled vehicle 1 in the basic posture state.

The roll moment inertial force component Mi is a moment of the sum of aninertial force component according to a temporal change rate(translational acceleration) of the translational moving velocity(lateral velocity) in the lateral direction (Y-axis direction) of thetwo-wheeled vehicle 1 which is produced during the traveling of thetwo-wheeled vehicle 1 in the steered state of the front wheel 3 f, andan inertial force component according to the centrifugal force at thetime of turning of the two-wheeled vehicle 1.

Therefore, when the lateral velocity, or, the translational movingvelocity in the lateral direction (Y-axis direction) of the two-wheeledvehicle 1 (specifically, translational moving velocity in the Y-axisdirection of the two-wheeled vehicle 1 at the position of the origin ofthe aforesaid XYZ coordinate system) is denoted as Voy, its temporalchange rate (first order differential) is denoted as Voy_dot, the movingvelocity in the longitudinal direction (X-axis direction) of the vehiclebody 2 (i.e. the traveling speed of the two-wheeled vehicle 1) isdenoted as Vox, and the angular velocity in the yaw direction (about theZ axis) of the vehicle body 2 is denoted as ωz, then the roll momentinertial force component Mi in the two-mass-point model can be obtainedby, for example, the following expression (8).

$\begin{matrix}\begin{matrix}{{Mi} = {{{Voy\_ dot}*m\; 1*h^{\prime}} + {\omega\; z*{Vox}*m\; 1*h^{\prime}}}} \\{= {\left( {{Voy\_ dot} + {\omega\; z*{Vox}}} \right)*m\; 1*h^{\prime}}}\end{matrix} & (8)\end{matrix}$

Here, Voy_dot*m1*h′ represents the inertial force component according tothe temporal change rate Voy_dot of the lateral velocity Voy of thetwo-wheeled vehicle 1, and ωz*Vox*m1*h′ represents the inertial forcecomponent according to the centrifugal force. Further, ωz*Vox representsthe centrifugal acceleration.

In the present embodiment, the control device 60 is configured to carryout the control processing established on the basis of thetwo-mass-point model described above. In this case, the control device60 controls the posture (inclination angle) in the roll direction of thevehicle body 2 by controlling the inverted pendulum mass point lateralmovement amount Pb_diff_y through the steering of the front wheel 3 f.

Further, in this control, when the operator seated on the boardingsection 4 of the vehicle body 2 of the two-wheeled vehicle 1 shifts thebody weight in the lateral direction of the vehicle body 2 at the timeof turning of the two-wheeled vehicle 1 or the like and, thus, thecenter of gravity of the operator is displaced laterally to the rightside or left side from a position on the plane of symmetry of thevehicle body 2, the first steering actuator 15 is controlled so as toapply to the vehicle body 2 a moment component in the direction ofincreasing such lateral displacement (a moment component in the rolldirection).

FIG. 7A shows the positional relationship of the center of gravity Gd ofthe operator, the center of gravity Gb of the two-wheeled vehicle 1alone, excluding the operator, and the overall center of gravity G inthe state where the center of gravity Gd of the operator is located onthe plane of symmetry of the vehicle body 2 (in the absence of lateraldisplacement of the center of gravity Gd). This state corresponds to theso-called “lean-with” state. In this state, the centers of gravity Gdand Gb are on the plane of symmetry, and thus, the overall center ofgravity G is also on the plane of symmetry. It should be noted that theposition of the center of gravity Gd of the operator in this statecorresponds to the predetermined reference position in the presentinvention.

FIG. 7B shows the positional relationship of the above-described centersof gravity Gd, Gb, and G in the state where the center of gravity Gd ofthe operator is displaced in the lateral direction of the vehicle body 2from the plane of symmetry of the vehicle body 2 in the same directionas the turning direction of the two-wheeled vehicle 1 (or theinclination direction of the vehicle body 2). FIG. 7C shows thepositional relationship of the above-described centers of gravity Gd,Gb, and G in the state where the center of gravity Gd of the operator isdisplaced in the lateral direction of the vehicle body 2 from the planeof symmetry of the vehicle body 2 in the direction opposite to theturning direction of the two-wheeled vehicle 1 (or the inclinationdirection of the vehicle body 2).

The state in FIG. 7B corresponds to the so-called “lean-in” state, andthe state in FIG. 7C corresponds to the so-called “lean-out” state. Inthese states, the center of gravity Gd of the operator is displacedlaterally from a position on the plane of symmetry, and thus, theoverall center of gravity G is also displaced laterally from a positionon the plane of symmetry.

Therefore, applying to the vehicle body 2 a moment component in thedirection of increasing lateral displacement (a moment component in theroll direction) when the center of gravity of the operator is displacedlaterally from the reference position (a position on the plane ofsymmetry of the vehicle body 2) to the lean-in state means, in otherwords, applying to the vehicle body 2 a moment component in thedirection of reducing the inclination in the roll direction of thevehicle body 2 (to make the inclination angle in the roll directionapproach zero). Further, applying to the vehicle body 2 a momentcomponent in the direction of increasing lateral displacement (a momentcomponent in the roll direction) when the center of gravity of theoperator is displaced laterally from the reference position to thelean-out state means, in other words, applying to the vehicle body 2 amoment component in the direction of further increasing the inclinationin the roll direction of the vehicle body 2.

The functions of the control device 60 for carrying out such controlprocessing will now be described specifically. In the followingdescription, the suffix “_act” is added to the reference characters of agiven state quantity, such as a steering angle of the front wheel 3 f orthe like, as a sign indicating an actual value or its observed value(detected value or estimate). For a desired value, the suffix “_cmd” isadded.

The control device 60 includes, as functions implemented when the CPUexecutes installed programs (functions implemented by software) or asfunctions implemented by hardware configurations, the functions shown bythe block diagram in FIG. 8.

That is, the control device 60 includes: an estimated inverted pendulummass point lateral movement amount calculating section 81 whichcalculates an estimate of an actual value Pb_diff_y_act (hereinafter,referred to as “estimated inverted pendulum mass point lateral movementamount Pb_diff_act”) of an inverted pendulum mass point lateral movementamount Pb_diff_y representing a movement amount in the Y-axis direction(lateral direction of the vehicle body 2) of the inverted pendulum masspoint 71 of the two-wheeled vehicle 1, an estimated inverted pendulummass point lateral velocity calculating section 82 which calculates anestimate of an actual value Vby_act (hereinafter, referred to as“estimated inverted pendulum mass point lateral velocity Vby_act”) of aninverted pendulum mass point lateral velocity Vby representing atranslational velocity in the Y-axis direction of the inverted pendulummass point 71, a rider's center-of-gravity lateral displacement indexvalue calculating section 83 which calculates an index value(hereinafter, this may be referred to as “rider's center-of-gravitylateral displacement index value”) representing the degree ofdisplacement of the center of gravity of the operator (degree ofdisplacement in the Y-axis direction from the plane of symmetry of thevehicle body 2) caused by the shift of the operator's weight in thelateral direction (Y-axis direction), and a desired posture statedetermining section 84 which determines a desired value Pb_diff_y_cmd(hereinafter, referred to as “desired inverted pendulum mass pointlateral movement amount Pb_diff_y_cmd”) of the inverted pendulum masspoint lateral movement amount Pb_diff_y and a desired value Vby_cmd(hereinafter, referred to as “desired inverted pendulum mass pointlateral velocity Vby_cmd”) of the inverted pendulum mass point lateralvelocity Vby.

Here, in the present embodiment, the rider's center-of-gravity lateraldisplacement index value calculating section 83 calculates, as therider's center-of-gravity lateral displacement index value, an estimateof a lateral displacement amount Pb_err (in the Y-axis direction fromthe plane of symmetry of the vehicle body 2) (hereinafter, referred toas “estimated inverted pendulum mass point lateral displacement Pb_err”)of the inverted pendulum mass point 71 which is caused in response tothe lateral displacement of the center of gravity of the operator fromthe plane of symmetry of the vehicle body 2.

The control device 60 further includes: a posture control arithmeticsection 85 which determines, as primary control inputs (manipulatedvariables) for controlling the posture in the roll direction of thevehicle body 2, a desired value δf1_cmd (hereinafter, referred to as“desired first steering angle δf1_cmd”) of the first steering angle δf1of the front wheel 3 f, a desired value δf1_dot_cmd (hereinafter,referred to as “desired first steering angular velocity δf1_dot_cmd”) ofa first steering angular velocity δf1_dot which is a temporal changerate of the first steering angle δf1, and a desired value δf1_dot2_cmd(hereinafter, referred to as “desired first steering angularacceleration δf1_dot2_cmd”) of a first steering angular accelerationδf1_dot2 which is a temporal change rate of the first steering angularvelocity δf1_dot, a second steering angle command determining section 86which determines a desired value δf2_cmd (hereinafter, referred to as“desired second steering angle δf2_cmd”) of the second steering angleδf2 of the front wheel 3 f, a desired value δf2_dot_cmd (hereinafter,referred to as “desired second steering angular velocity δf2_dot_cmd”)of a second steering angular velocity δf2_dot which is a temporal changerate of the second steering angle δf2, and a desired value δf2_dot2_cmd(hereinafter, referred to as “desired second steering angularacceleration δf2_dot2_cmd”) of a second steering angular accelerationδf2_dot2 which is a temporal change rate of the second steering angularvelocity δf2_dot, and a desired traveling speed determining section 87which determines a desired value Vox_cmd (hereinafter, referred to as“desired traveling speed Vox_cmd”) of the traveling speed Vox of thetwo-wheeled vehicle 1.

The control device 60 carries out the processing in the above-describedfunctional sections successively at predetermined control processingcycles. The control device 60 controls the first steering actuator 15 inaccordance with the desired first steering angle δf1_cmd, the desiredfirst steering angular velocity δf1_dot_cmd, and the desired firststeering angular acceleration δf1_dot2_cmd determined by the posturecontrol arithmetic section 85.

Further, the control device 60 controls the second steering actuator 37in accordance with the desired second steering angle δf2_cmd, thedesired second steering angular velocity δf2_dot_cmd, and the desiredsecond steering angular acceleration δf2_dot2_cmd determined by thesecond steering angle command determining section 86.

Furthermore, the control device 60 controls the front-wheel drivingactuator 7 in accordance with the desired traveling speed Vox_cmddetermined by the desired traveling speed determining section 87.

Details of the control processing in the control device 60 will bedescribed below. In the arithmetic processing described below inrelation to the control processing in the control device 60, values ofthe parameters m, m1, m2, and h′ regarding the two-mass-point modeldescribed above and values of the parameters θcs, Lf, Lr, and Rgregarding the specification of the two-wheeled vehicle 1 are used. Thevalues of these parameters m, m1, m2, h′, θcs, Lf. Lr, and Rg are setvalues determined in advance. Further. “g” in the arithmetic processingrepresents the gravitational acceleration constant.

The control device 60 carries out the processing in the estimatedinverted pendulum mass point lateral movement amount calculating section81 at each control processing cycle.

As shown in FIG. 9, the estimated inverted pendulum mass point lateralmovement amount calculating section 81 receives: a detected roll angleϕb_act which is a detected value of the inclination angle ϕb in the rolldirection (hereinafter, referred to as “roll angle ϕb”) of the vehiclebody 2, and a detected first steering angle δf1_act as a detected valueof the first steering angle δf1 and a detected second steering angleδf2_act as a detected value of the second steering angle δf2 of thefront wheel 3 f.

The detected roll angle ϕb_act is a detected value (observed value)indicated by an output from the vehicle-body inclination detector 61,the detected first steering angle δf1_act is a detected value (observedvalue) indicated by an output from the first steering angle detector 62,and the detected second steering angle δf2_act is a detected value(observed value) indicated by an output from the second steering angledetector 63.

The estimated inverted pendulum mass point lateral movement amountcalculating section 81 calculates an estimated inverted pendulum masspoint lateral movement amount Pb_diff_y_act by the arithmetic processingshown by the block and line diagram in FIG. 9. That is, the estimatedinverted pendulum mass point lateral movement amount calculating section81 calculates Pb_diff_y_act by the arithmetic processing of thefollowing expressions (10a) to (10c).Pb_diff_y_1=−h′*b_act  (10a)Pb_diff_y_2=(Plf1y(δf1_act)+Plf2y(δf1_act+δf2_act))*(Lr/L)  (10b)Pb_diff_y_act=Pb_diff_y_1+Pb_diff_y_2  (10c)

In FIG. 9, processing sections 81-1, 81-2, and 81-3 represent processingsections which perform the arithmetic processing of the expressions(10a), (10b), and (10c), respectively.

Here, Pb_diff_y_1 calculated by the expression (10a) in the processingsection 81-1 is a component, as part of Pb_diff_y_act, which is definedaccording to the detected roll angle ϕb_act. It should be noted that inthe arithmetic processing of the expression (10a), sin(ϕb_act) isapproximated by ϕb_act.

Pb_diff_y_2 calculated by the expression (10b) in the processing section81-2 is a component, as part of Pb_diff_y_act, which is definedaccording to the steering angles (detected first steering angle δf1_actand detected second steering angle δf2_act) of the front wheel 3 f. ThisPb_diff_y_2 corresponds to an estimate of the movement amount q in theY-axis direction of the ground surface mass point 72 according to thesteering of the front wheel 3 f.

Plf1 y(δf1_act) in the expression (10b) is a function value which isdetermined in a processing section 81-2-1 in FIG. 9, from the value ofδf1_act, by a preset conversion function Plf1 y(δf1). This conversionfunction Plf1 y(δf1) is configured, for example, by a mapping or anarithmetic expression. In the present embodiment, the conversionfunction Plf1 y(δf1) has been set, as illustrated by the graph in theprocessing section 81-2-1, such that the value of Plf1 y decreases froma value on the positive side to a value on the negative side as thevalue of δf1 increases (from a value on the negative side to a value onthe positive side).

Further. Plf2 y(δf1_act+δf2_act) in the expression (10b) is a functionvalue which is determined by a preset conversion function Plf2y(δf1+δf2) from the value of δf1_act+δf2_act in a processing section81-2-2 in FIG. 9. This conversion function Plf2 y(δf1+δf2) isconfigured, for example, by a mapping or an arithmetic expression. Inthe present embodiment, the conversion function Plf2 y(δf1+δf2) has beenset, as illustrated by the graph in the processing section 81-2-2, suchthat the value of Plf2 y increases from a value on the negative side toa value on the positive side as the value of δf1+δf2 increases (from avalue on the negative side to a value on the positive side).

Then, from Pb_diff_y_1 and Pb_diff_y_2 calculated by the expressions(10a) and (10b), respectively, the estimated inverted pendulum masspoint lateral movement amount Pb_diff_y_act is calculated by thearithmetic processing (expression (10c)) in the processing section 81-3.

In the above-described manner, the estimated inverted pendulum masspoint lateral movement amount calculating section 81 performs thearithmetic processing of the above expressions (10a) to (10c), at eachcontrol processing cycle, to thereby calculate the estimated invertedpendulum mass point lateral movement amount Pb_diff_y_act.

Supplementally, the conversion functions in the processing sections81-2-1 and 81-2-2 may be set in such a way as to obtain a value of Plf1y(δf1_act)*(Lr/L) in the processing section 81-2-1 and a value of Plf2y(δf1_act+δf2_act)*(Lr/L) in the processing section 81-2-2.

In this case, the sum of the output values from the processing sections81-2-1 and 81-2-2, as it is, is obtained as Pb_diff_y_2.

Further, the processing section 81-2, which obtains Pb_diff_y_2, may beconfigured to obtain Pb_diff_y_2 directly from a set of the values ofδf1_act and δf2_act, for example, by a two-dimensional mapping or thelike.

Furthermore, in the processing section 81-2, when the magnitudes(absolute values) of δf1_act and δf2_act are sufficiently small,Pb_diff_y_2 may be obtained through the computation of the right side ofthe above expression (4).

Next, the control device 60 carries out the processing in the estimatedinverted pendulum mass point lateral velocity calculating section 82.

As shown in FIG. 10, the estimated inverted pendulum mass point lateralvelocity calculating section 82 receives: an estimated inverted pendulummass point lateral movement amount Pb_diff_y_act calculated in theestimated inverted pendulum mass point lateral movement amountcalculating section 81, a detected first steering angle δf1_act and adetected second steering angle δf2_act of the front wheel 3 f, and anestimated front-wheel rotational transfer velocity Vf_act which is anestimate (observed value) of the rotational transfer velocity Vf of thefront wheel 3 f.

The estimated front-wheel rotational transfer velocity Vf_act is avelocity which is calculated by multiplying the detected value (observedvalue) of the rotational angular velocity of the front wheel 3 f,indicated by an output from the aforesaid front-wheel rotational speeddetector 65, by the predetermined effective rolling radius of the frontwheel 3 f.

The estimated inverted pendulum mass point lateral velocity calculatingsection 82 carries out the arithmetic processing shown by the block andline diagram in FIG. 10 to calculate an estimated inverted pendulum masspoint lateral velocity Vby_act. That is, the estimated inverted pendulummass point lateral velocity calculating section 82 calculates theestimated inverted pendulum mass point lateral velocity Vby_act by thearithmetic processing of the following expressions (11a) to (11d).Pb_diff_dot_y_act=differential (temporal change rate) ofPb_diff_y_act  (11a)δ′f_act=(δf1_act+δf2_act)*cos(θcs)  (11b)Voy_act=sin(δ′f_act)*Vf_act*(Lr/L)  (11c)Vby_act=Pb_diff_dot_y_act+Voy_act  (11d)

In FIG. 10, a processing section 82-1 represents a processing sectionwhich performs the arithmetic processing (differential operation) of theexpression (11a), a processing section 82-2 represents a processingsection which performs the arithmetic processing of the expressions(11b) and (11c), and a processing section 82-3 represents a processingsection which performs the arithmetic processing of the expression(11d).

Here, Pb_diff_dot_y_act calculated in the processing section 82-1 by theexpression (11a) is an estimate of the moving velocity, as seen in theaforesaid XYZ coordinate system, (relative velocity with respect to theorigin of the XYZ coordinate system) of the inverted pendulum mass point71 in the Y-axis direction.

Further, δ′f_act calculated in the processing section 82-2 by theexpression (11b) is an estimate (hereinafter, referred to as “estimatedfront-wheel effective steering angle δ′f_act”) of a front-wheeleffective steering angle δ′f which is a rotational angle of the frontwheel 3 f in the yaw direction (about the Z axis) by the steering of thefront wheel 3 f.

The front-wheel effective steering angle δ′f is, more specifically, anangle made by the line of intersection of the contact ground surface Sand the rotational plane of the front wheel 3 f (plane passing throughthe center of the axle of the front wheel 3 f and orthogonal to the axlecenterline of the front wheel 3 f) with respect to the longitudinaldirection (X-axis direction) of the vehicle body 2.

In the case where the roll angle ϕb of the vehicle body 2 is relativelysmall, the estimate of this δ′f, or, the estimated front-wheel effectivesteering angle δ′f_act can be calculated approximately by the aboveexpression (11b).

It should be noted that in order to further improve the accuracy ofS′f_act, δ′f_act may be obtained by a preset mapping fromδf1_act+δf2_act, or from δf1_act, δf2_act, for example. Alternatively,in order to still further improve the accuracy of δ′f_act, δ′f_act maybe obtained by a preset mapping from δf1_act+δf2_act or δf1_act,δf2_act, and a detected roll angle ϕb_act of the vehicle body 2, forexample.

Further, Voy_act calculated in the processing section 82-2 by theexpression (11c) using the estimated front-wheel effective steeringangle δ′f_act corresponds to an estimate of the lateral velocity of thetwo-wheeled vehicle 1 (more specifically, translational moving velocityin the Y-axis direction of the two-wheeled vehicle 1 at the position ofthe origin of the aforesaid XYZ coordinate system set for thetwo-wheeled vehicle 1) which is produced during the traveling of thetwo-wheeled vehicle 1 while the front wheel 3 f is being steered.

Then, from Pb_diff_dot_y_act and Voy_act calculated by the expressions(11a) and (11c), respectively, the estimated inverted pendulum masspoint lateral velocity Vby_act is calculated by the arithmeticprocessing (expression (11d)) in the processing section 82-3.

In the above-described manner, the estimated inverted pendulum masspoint lateral velocity calculating section 82 performs the arithmeticprocessing of the above expressions (11a), (11b), (11c), and (11d), ateach control processing cycle, to thereby calculate the estimatedinverted pendulum mass point lateral velocity Vby_act.

The control device 60 further carries out the processing in the rider'scenter-of-gravity lateral displacement index value calculating section83. As shown in FIG. 11, the rider's center-of-gravity lateraldisplacement index value calculating section 83 receives: an estimatedinverted pendulum mass point lateral movement amount Pb_diff_y_actcalculated in the estimated inverted pendulum mass point lateralmovement amount calculating section 81, a detected first steering angleδf1_act and a detected second steering angle δf2_act of the front wheel3 f, and an estimated front-wheel rotational transfer velocity Vf_actdescribed above.

The rider's center-of-gravity lateral displacement index valuecalculating section 83 calculates an estimated inverted pendulum masspoint lateral displacement Pb_err as a rider's center-of-gravity lateraldisplacement index value, through the arithmetic processing shown by theblock and line diagram in FIG. 11. In this case, the rider'scenter-of-gravity lateral displacement index value calculating section83 is configured as an observer.

Specifically, the rider's center-of-gravity lateral displacement indexvalue calculating section 83 calculates an estimate of the roll momentinertial force component Mi, an estimate of the roll moment floorreaction force component Mp, and an estimate of the roll moment groundsurface mass point component M2 by a roll moment inertial forcecomponent calculating section 83-2, a roll moment floor reaction forcecomponent calculating section 83-3, and a roll moment ground surfacemass point component calculating section 83-4, respectively, on thebasis of the input values of δf1_act, δf2_act, and Vf_act. The specificprocessing in the calculating sections 83-2, 83-3, and 83-4 will bedescribed later.

Then, the rider's center-of-gravity lateral displacement index valuecalculating section 83 carries out, in a processing section 83-5,arithmetic processing based on a dynamic model taking account of lateraldisplacement of the inverted pendulum mass point 71 due to lateraldisplacement of the center of gravity of the operator, on the basis ofthe estimates of Mi, Mp, and M2, the input value of Pb_diff_y_act, and avalue (last time's value) Pb_err_p of the estimated inverted pendulummass point lateral displacement Pb_err calculated in the last time'scontrol processing cycle, to thereby calculate an estimate of thetranslational acceleration Pb_diff_dot2_y in the Y-axis direction of theinverted pendulum mass point 71.

Stated differently, the last time's value Pb_err_p corresponds to thelatest one of the estimated inverted pendulum mass point lateraldisplacements Pb_err calculated up to then.

Here, the dynamic model (equation of motion of the inverted pendulummass point 71) taking account of the lateral displacement of theinverted pendulum mass point 71 due to the lateral displacement of thecenter of gravity of the operator is expressed by the equation of motionobtained by replacing Pb_diff_y on the right side of the aboveexpression (2) with Pb_diff_y_act+Pb_err.

Therefore, the arithmetic processing in the processing section 83-5 iscarried out in accordance with the following expression (12a).Pb_diff_dot2_y=(m1*g*(Pb_diff_y_act+Pb_err_p)−Mp−M2−Mi)/(m1*h′)  (12a)

Then, the rider's center-of-gravity lateral displacement index valuecalculating section 83 integrates, in a processing section 83-6,Pb_diff_dot2_, calculated by the above expression (12a), to therebycalculate a first estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_1 as a first estimate of the moving velocity (asseen in the XYZ coordinate system) in the Y-axis direction of theinverted pendulum mass point 71, as shown by the following expression(12b).Pb_diff_dot_y_1=integral of Pb_diff_dot2_y  (12b)

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 83 performs, in a processing section 83-1, adifferential operation on the input value of Pb_diff_y_act, to therebycalculate a second estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_2 as a second estimate of the moving velocity (asseen in the XYZ coordinate system) in the Y-axis direction of theinverted pendulum mass point 71, as shown by the following expression(12c).Pb_diff_dot_y_2=differential (temporal change rate) ofPb_diff_y_act  (12c)

It should be noted that Pb_diff_dot_y_2 calculated by the expression(12c) is the same as Pb_diff_dot_y_act calculated by the aboveexpression (11a) by the estimated inverted pendulum mass point lateralvelocity calculating section 82. Therefore, Pb_diff_dot_y_act calculatedin the estimated inverted pendulum mass point lateral velocitycalculating section 82 may be used, without modification, as the secondestimated inverted pendulum mass point lateral velocity Pb_diff_dot_y_2.

Here, the estimated inverted pendulum mass point lateral movement amountPb_diff_y_act is calculated by the estimated inverted pendulum masspoint lateral movement amount calculating section 81 assuming that nolateral displacement of the center of gravity of the operator (from aposition on the plane of symmetry of the vehicle body 2) has occurred.Therefore, the second estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_2 calculated by the expression (12c) correspondsto an estimate of the moving velocity in the Y-axis direction of theinverted pendulum mass point 71 on the assumption that there is nolateral displacement of the center of gravity of the operator.

Therefore, the deviation between this second estimated inverted pendulummass point lateral velocity Pb_diff_dot_y_2 and the first estimatedinverted pendulum mass point lateral velocity Pb_diff_dot_y_1,calculated dynamically according to the above expressions (12a) and(12b), becomes a value depending on the inverted pendulum mass pointlateral displacement amount Pb_err caused by the lateral displacement ofthe center of gravity of the operator.

Thus, the rider's center-of-gravity lateral displacement index valuecalculating section 83 calculates the estimated inverted pendulum masspoint lateral displacement Pb_err in a processing section 83-7 by thearithmetic processing of the following expression (12d).

$\begin{matrix}\begin{matrix}{{Pb\_ err} = {\left( {{{Pb\_ diff}{\_ dot}{\_ y}\_ 2} - {{Pb\_ diff}{\_ dot}{\_ y}\_ 1}} \right)*}} \\{{Kestm}*{\left( {m\; 1*h^{\prime}} \right)/\left( {m\; 1*g} \right)}} \\{= {\left( {{{Pb\_ diff}{\_ dot}{\_ y}\_ 2} - {{Pb\_ diff}{\_ dot}{\_ y}\_ 1}} \right)*}} \\{{Kestm}*{h^{\prime}/g}}\end{matrix} & \left( {12d} \right)\end{matrix}$

Kestm used in the arithmetic processing of this expression (12d) is apredetermined gain of a predetermined value. It should be noted thatPb_err calculated by this expression (12d) takes a positive value whenthe center of gravity of the operator is displaced on the lean-in sidefrom a position on the plane of symmetry of the vehicle body 2, andtakes a negative value when it is displaced on the lean-out sidetherefrom.

Supplementally, Kestm*h′/g in the expression (12d) may be set in advanceas a single gain value.

Further, in the block and line diagram in FIG. 11, a last time's value(=Pb_err_p*m1*g) of (Pb_diff_dot_y_2−Pb_diff_dot_y_1)*Kestm*(m1*h′) isinput to the processing section 83-5 from the processing section 83-7.Alternatively, a last time's value Pb_err_p of the estimated invertedpendulum mass point lateral displacement Pb_err, for example, may beinput directly to the processing section 83-5.

In the above-described manner, the rider's center-of-gravity lateraldisplacement index value calculating section 83 calculates the estimatesof Mi, Mp, M2, and uses these estimates and the estimated invertedpendulum mass point lateral movement amount Pb_diff_y_act to perform thearithmetic processing of the expressions (12a) to (12d), to therebycalculate the estimated inverted pendulum mass point lateraldisplacement Pb_err.

In this case, the estimates of Mi, Mp, and M2 are calculated in themanner described below.

First, the roll moment inertial force component calculating section 83-2in the rider's center-of-gravity lateral displacement index valuecalculating section 83 calculates an estimate of the roll momentinertial force component Mi by the arithmetic processing shown by theblock and line diagram in FIG. 12. That is, the roll moment inertialforce component calculating section 83-2 calculates the estimate of theroll moment inertial force component Mi by the arithmetic processing ofthe following expressions (13a) to (13f).δ′f_act=(δf1_act+δf2_act)*cos(θcs)  (13a)Voy_act=sin(δ′f_act)*Vf_act*(Lr/L)  (13b)Voy_dot_act=differential (temporal change rate) of Voy_act  (13c)θz_act=sin(δ′f_act)*Vf_act*(1/L)  (13d)Vox_act=cos(δ′f_act)*Vf_act  (13e)Mi=(Voy_dot_act+ωz_act*Vox_act)*m*h′  (13f)

In FIG. 12, a processing section 83-2-1 represents a processing sectionwhich performs the arithmetic processing of the expressions (13a) and(13b), a processing section 83-2-2 represents a processing section whichperforms the arithmetic processing (differential operation) of theexpression (13c), a processing section 83-2-3 represents a processingsection which performs the arithmetic processing of the expressions(13a) and (13d), a processing section 83-2-4 represents a processingsection which performs the arithmetic processing of the expressions(13a) and (13e), and a processing section 83-2-5 represents a processingsection which performs the arithmetic processing of the expression(13f).

Here, the arithmetic processing (expressions (13a) and (13b)) in theprocessing section 83-2-1 is the same as the arithmetic processing inthe processing section 82-2 in the aforesaid estimated inverted pendulummass point lateral velocity calculating section 82. Therefore, thisarithmetic processing yields an estimate Voy_act of the lateral velocityof the two-wheeled vehicle 1 (specifically, translational movingvelocity in the Y-axis direction of the two-wheeled vehicle 1 at theposition of the origin of the aforesaid XYZ coordinate system set forthe two-wheeled vehicle 1) which is produced during the traveling of thetwo-wheeled vehicle 1 while the front wheel 3 f is being steered.

Then, a differential Voy_dot_act of this estimate Voy_act, i.e. anestimate Voy_dot_act of a temporal change rate of the lateral velocity(translational moving velocity in the Y-axis direction) of thetwo-wheeled vehicle 1, is calculated by the arithmetic processing(expression (13c)) in the processing section 83-2-2.

Further, by the arithmetic processing (expressions (13a) and (13d)) inthe processing section 83-2-3, an estimate ωz_act (hereinafter, referredto as “estimated yaw rate ωz_act”) of the angular velocity ωz in the yawdirection (about the Z axis) of the two-wheeled vehicle 1 is calculated.

Further, by the arithmetic processing (expressions (13a) and (13e)) inthe processing section 83-2-4, an estimate Vox_act (hereinafter,referred to as “estimated traveling speed Vox_act”) of the movingvelocity in the longitudinal direction (X-axis direction) of the vehiclebody 2 of the two-wheeled vehicle 1 (i.e. traveling speed Vox of thetwo-wheeled vehicle 1) is calculated.

The arithmetic processing (expression (13f)) in the processing section83-2-5 is then performed using Voy_dot_act, ωz_act, and Vox_actcalculated in the processing sections 83-2-2, 83-2-3, and 83-2-4,respectively. An estimate of the roll moment inertial force component Miis thus calculated.

It should be noted that the expression (13f) is obtained from the aboveexpression (8), by using Voy_dot_act, ωz_act, and Vox_act as the valuesof Voy_dot, ωz, and Vox, respectively, therein.

In the above-described manner, the roll moment inertial force componentcalculating section 83-2 performs the arithmetic processing of the aboveexpressions (13a) to (13f), to thereby calculate an estimate of the rollmoment inertial force component Mi.

Supplementally, the estimated front-wheel effective steering angleδ′f_act calculated by the expression (13a) is the same as the valuecalculated in the estimated inverted pendulum mass point lateralvelocity calculating section 82. Therefore, in the arithmetic processingof the expressions (13b), (13c), and (13d), the estimated front-wheeleffective steering angle δ′f_act calculated in the estimated invertedpendulum mass point lateral velocity calculating section 82 may be usedwithout modification. In this case, of the arithmetic processing in theroll moment inertial force component calculating section 83-2, thearithmetic processing (expression (13a)) for calculating δ′f_act isunnecessary.

Further, the processing section 83-2-1 may be omitted, and the estimateVoy_act of the lateral velocity of the two-wheeled vehicle 1, calculatedin the estimated inverted pendulum mass point lateral velocitycalculating section 82, may be used, without modification, in thearithmetic processing (expression (13c)) in the processing section83-2-2.

Further, for example in the case where an angular velocity sensor fordetecting an angular velocity in the yaw direction is mounted on thevehicle body 2 of the two-wheeled vehicle 1, a detected value of theangular velocity in the yaw direction indicated by an output from thatangular velocity sensor may be used as a value of ωz_act in theexpression (13f). In this case, the arithmetic processing (expression(13d)) in the processing section 83-2-3 is unnecessary.

Furthermore, for example in the case where a rear-wheel rotational speeddetector for detecting a rotational speed (angular velocity) of the rearwheel 3 r of the two-wheeled vehicle 1 is mounted on the two-wheeledvehicle 1, an estimate of the translational moving velocity of the rearwheel 3 r obtained by multiplying the detected value of the rotationalspeed of the rear wheel 3 r, indicated by an output from that rear-wheelrotational speed detector, by the effective rolling radius of the rearwheel 3 r may be used as a value of Vox_act in the expression (13f). Inthis case, the arithmetic processing (expression (13e)) in theprocessing section 83-2-4 is unnecessary.

Next, the roll moment floor reaction force component calculating section83-3 in the rider's center-of-gravity lateral displacement index valuecalculating section 83 calculates an estimate of the roll moment floorreaction force component Mp by the arithmetic processing shown by theblock and line diagram in FIG. 13. That is, the roll moment floorreaction force component calculating section 83-3 calculates theestimate of the roll moment floor reaction force component Mp by thearithmetic processing of the following expressions (14a) to (14c).p1=Pfy(δf1_act+δf2_act)*(Lr/L)  (14a)p2=(Plf1y(δf1_act)+Plf2y(δf1_act+δf2_act))*(Lr/L)*(−Rg/h′)  (14b)Mp=(p1+p2)*m*g  (14c)

In FIG. 13, a processing section 83-3-1 represents a processing sectionwhich performs the arithmetic processing of the expression (14a), aprocessing section 83-3-2 represents a processing section which performsthe arithmetic processing of the expression (14b), and a processingsection 83-3-3 represents a processing section which performs thearithmetic processing of the expression (14c).

Here, p1 calculated by the arithmetic processing (expression (14a)) inthe processing section 83-3-1 is a movement amount component which ispart of the movement amount p in the Y-axis direction (hereinafter,referred to as “lateral movement amount p”) of the COP from the positionof the origin of the XYZ coordinate system and which is produced inresponse to the event that the front wheel 3 f rolls in the lateraldirection (Y-axis direction) during the steering of the front wheel 3 fand, hence, the ground contact point of the front wheel 3 f moves in theY-axis direction. The value of this movement amount component p1corresponds to the value of the first term on the right side of theabove expression (6).

Further, Pfy(δf1_act+δf2_act) in the expression (14a) is a functionvalue which is determined by a preset conversion function Pfy(δf1+δf2)from the value of δf1_act+δf2_act in a processing section 83-3-1-1 inthe processing section 83-3-1 in FIG. 13. This conversion functionPfy(δf1+δf2) is configured, for example, by a mapping or an arithmeticexpression. The conversion function Pfy(δf1+δf2) has been set, asillustrated by the graph in the processing section 83-3-1-1, such thatthe value of Pfy increases monotonically from a value on the negativeside to a value on the positive side as the value of δf1+δf2 increases(from a value on the negative side to a value on the positive side).

Further, p2 calculated by the arithmetic processing (expression (14b))in the processing section 83-3-2 is a movement amount component which ispart of the lateral movement amount p of the COP and which is produceddue to the movement in the Y-axis direction of the ground contact pointof the front wheel 3 f as the front wheel 3 f leans during the steeringof the front wheel 3 f. This movement amount component p2 corresponds tothe value of the second term on the right side of the above expression(6).

In this case, the arithmetic processing of the computation of the rightside of the expression (14b) excluding the multiplication of (−Rg/h′),i.e. the arithmetic processing in a processing section 83-3-2-1 in theprocessing section 83-3-2, is the same as the processing (of calculatingPb_diff_y_2) of the processing section 81-2 in the arithmetic processingof the aforesaid estimated inverted pendulum mass point lateral movementamount calculating section 81.

Therefore, the expression (14b) is equivalent to the followingexpression (14b′).p2=Pb_diff_y_2*(−Rg/h′)  (14b′)

Further, the arithmetic processing (expression (14c)) in the processingsection 83-3-3 is the arithmetic processing of calculating the rollmoment floor reaction force component Mp by an expression correspondingto the above expression (5) in which p1+p2 is used as the value of p.

In the above-described manner, the roll moment floor reaction forcecomponent calculating section 83-3 calculates an estimate of the rollmoment floor reaction force component Mp by the arithmetic processing ofthe above expressions (14a) to (14c).

Supplementally, in the processing section 83-3-1, instead of theconversion function Pfy(δf1+δf2), a conversion function which obtains avalue (=p1) of (Pfy(δf1_act+δf2_act)*(Lr/L)) as a function value may beused. In this case, p1 is obtained directly from the conversionfunction.

Further, the modifications explained supplementally about the processingsection 81-2 in the estimated inverted pendulum mass point lateralmovement amount calculating section 81 may also be adopted for theprocessing section 83-3-2-1 in the processing section 83-3-2.

Further, in the arithmetic processing in the processing section 83-3-2,a conversion function which obtains a value of (Plf1y(δf1_act)*(Lr/L)*(−Rg/h′)) as a function value may be used instead ofthe conversion function Plf1 y(δf1), and a conversion function whichobtains a value of (Plf2 y(δf1_act+δf2_act)*(Lr/L)*(−Rg/h′)) as afunction value may be used instead of the conversion function Plf2y(δf1+δf2). In this case, the sum of the output values of theseconversion functions is obtained as p2.

Both of p1 and p2 are function values of the set of δf1_act and δf2_actTherefore, an estimate of the lateral movement amount p of the COP orthe roll moment floor reaction force component Mp may be obtaineddirectly from the set of δf1_act and δf2_act by a two-dimensionalmapping or the like.

In the case where the magnitudes (absolute values) of δf1_act andδf2_act are sufficiently small, the lateral movement amount p of the COPmay be calculated by the arithmetic processing of the above expressions(4) and (6).

Next, the roll moment ground surface mass point component calculatingsection 83-4 in the rider's center-of-gravity lateral displacement indexvalue calculating section 83 calculates an estimate of the roll momentground surface mass point component M2 by the arithmetic processingshown by the block and line diagram in FIG. 14. That is, the roll momentground surface mass point component calculating section 83-4 calculatesthe estimate of the roll moment ground surface mass point component M2by the arithmetic processing of the following expressions (15a) and(15b).q=(Plf1y(δf1_act)+Plf2y(δf1_act+δf2_act))*(Lr/L)  (15a)M2=q*(−m2*g)  (15b)

In FIG. 14, a processing section 83-4-1 represents a processing sectionwhich performs the arithmetic processing of the expression (15a), and aprocessing section 83-4-2 represents a processing section which performsthe arithmetic processing of the expression (15b).

Here, q that is calculated by the arithmetic processing (expression(15a)) in the processing section 83-4-1 is a movement amount in theY-axis direction (hereinafter, referred to as “lateral movement amountq”) of the ground surface mass point 72 from the position of the originof the XYZ coordinate system.

In this case, the arithmetic processing in the processing section 83-4-1is the same as the arithmetic processing (of calculating Pb_diff_y_2) ofthe processing section 81-2 in the arithmetic processing of theaforesaid estimated inverted pendulum mass point lateral movement amountcalculating section 81. Therefore, in the arithmetic processing of theprocessing section 83-4-1, Pb_diff_y_2 is calculated as the lateralmovement amount q of the ground surface mass point 72.

Further, the arithmetic processing (expression (15b)) in the processingsection 83-4-2 is the arithmetic processing of calculating the rollmoment ground surface mass point component M2 by the same expression asthe aforesaid expression (3).

In the above-described manner, the roll moment ground surface mass pointcomponent calculating section 83-4 calculates an estimate of the rollmoment ground surface mass point component M2 by the arithmeticprocessing of the above expressions (15a) and (15b).

Supplementally, the modifications explained supplementally about theprocessing section 81-2 in the estimated inverted pendulum mass pointlateral movement amount calculating section 81 may also be adopted forthe processing section 83-4-1.

Further, a conversion function which obtains a value of (Plf1y(δf1_act)*(Lr/L)*(*(−m2*g)) as a function value may be used instead ofthe conversion function Plf1 y(δf1), and a conversion function whichobtains a value of (Plf2 y(δf1_act+δf2_act)*(Lr/L)*(−m2*g)) as afunction value may be used instead of the conversion function Plf2y(δf2). In this case, the sum of the output values of these conversionfunctions, as it is, is obtained as the roll moment ground surface masspoint component M2.

Further, an estimate of the lateral movement amount q of the groundsurface mass point 72 or the roll moment ground surface mass pointcomponent M2 may also be obtained directly from the set of δf1_act andδf2_act by a two-dimensional mapping or the like.

Furthermore, in the case where the magnitudes (absolute values) ofδf1_act and δf2_act are sufficiently small, the lateral movement amountq of the ground surface mass point 72 may be calculated by thearithmetic processing of the above expression (4).

Returning to FIG. 8, the control device 60 further carries out theprocessing in the desired posture state determining section 84.

In the present embodiment, the desired posture state determining section84 determines a desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd by the arithmetic processing of the followingexpressions (16a) and (16b), by using, for example, an estimate ωz_actof the angular velocity ωz in the yaw direction (about the Z axis) ofthe two-wheeled vehicle 1, calculated by the arithmetic processing ofthe above expression (13d), and an estimate Vox_act of the travelingspeed Vox of the two-wheeled vehicle 1 (moving velocity in the X-axisdirection of the vehicle body 2), calculated by the arithmeticprocessing of the expression (13e). In the present embodiment, thedesired posture state determining section 84 sets a desired invertedpendulum mass point lateral velocity Vby_cmd to zero.ϕb_lean=−Vox_act*ωz_act/m  (16a)Pb_diff_y_cmd=ϕb_lean*h′  (16b)

Here, ϕb_lean calculated by the arithmetic processing of the expression(16a) is a roll angle of the vehicle body 2 at which a moment in theroll direction produced by the gravitational force acting on thetwo-wheeled vehicle 1 and a moment in the roll direction produced by thecentrifugal force are balanced.

The desired posture state determining section 84 determinesPb_diff_y_cmd and Vby_cmd in the above-described manner. Supplementally,the desired inverted pendulum mass point lateral velocity Vby_cmd may bedetermined variably in accordance with, for example, the detected firststeering angle δf1_act and the detected second steering angle δf2_act.

Further, the desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd may be set to zero, for example. Alternatively, thedesired inverted pendulum mass point lateral movement amountPb_diff_y_cmd may be determined variably in accordance with, forexample, the detected first steering angle δf1_act and the detectedsecond steering angle δf2_act.

Next, the control device 60 carries out the processing in the posturecontrol arithmetic section 85. As shown in FIG. 15, the posture controlarithmetic section 85 receives: a desired inverted pendulum mass pointlateral movement amount Pb_diff_y_cmd and a desired inverted pendulummass point lateral velocity Vby_cmd determined in the desired posturestate determining section 84, an estimated inverted pendulum mass pointlateral movement amount Pb_diff_y_act calculated in the estimatedinverted pendulum mass point lateral movement amount calculating section81, an estimated inverted pendulum mass point lateral velocity Vby_actcalculated in the estimated inverted pendulum mass point lateralvelocity calculating section 82, and an estimated inverted pendulum masspoint lateral displacement Pb_err calculated in the rider'scenter-of-gravity lateral displacement index value calculating section83.

The posture control arithmetic section 85 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 15, to determine a desired first steering angle δf1_cmd, a desiredfirst steering angular velocity δf1_dot_cmd, and a desired firststeering angular acceleration δf1_dot2_cmd.

That is, the posture control arithmetic section 85 calculates thedesired first steering angular acceleration δf1_dot2_cmd by thearithmetic processing of the following expression (17a). Further, theposture control arithmetic section 85 integrates the desired firststeering angular acceleration δf1_dot2_cmd as shown by the followingexpression (17b) to calculate the desired first steering angularvelocity δf1_dot_cmd.

Further, the posture control arithmetic section 85 integrates thedesired first steering angular velocity δf1_dot_cmd as shown by thefollowing expression (17c) to calculate the desired first steering angleδf1_cmd.δf1_dot2_cmd=−K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act)−K2*(Vby_cmd−Vby_act)−K3*δf1_cmd_p−K4*f1_dot_cmd_p  (17a)δf1_dot_cmd=integral of δf1_dot2_cmd  (17b)δf1_cmd=integral of δf1_dot_cmd  (17c)

In FIG. 15, processing sections 85-1, 85-2, and 85-3 representprocessing sections which perform the arithmetic processing of theexpressions (17a), (17b), and (17c), respectively.

Here, Kdstb, K1, K2, K3, and K4 in the expression (17a) are gains ofpredetermined values. The values of these gains Kdstb, K1, K2, K3, andK4 are set variably in accordance with, for example, the estimatedtraveling speed Vox_act of the two-wheeled vehicle 1, or the detectedfirst steering angle δf1_act and the detected second steering angleδf2_act.

In this case, in the present embodiment, the values of the gains Kdstb,K1, K2, K3, and K4 are set such that the moment in the roll directionacting on the vehicle body 2 by the steering of the front wheel 3 faccording to δf1_dot2_cmd, δf1_dot_cmd, and δf1_cmd will become not solarge (such that the operator can lean the vehicle body 2 in the rolldirection relatively easily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb, K1, K2, K3, and K4 are allset such that they vary in accordance with the estimated traveling speedVox_act of the two-wheeled vehicle 1.

For example, the magnitudes of the gains K1, K2, K3, and K4 are all setvariably such that they become smaller as the estimated traveling speedVox_act of the two-wheeled vehicle 1 is higher.

δf1_cmd_p is a value (last time's value) of the desired first steeringangle δf1_cmd that was determined by the posture control arithmeticsection 85 in the last time's control processing cycle. δf1_dot_cmd_p isa value (last time's value) of the desired first steering angularvelocity δf1_dot_cmd that was determined by the posture controlarithmetic section 85 in the last time's control processing cycle.

Kdstb*Pb_err in the expression (17a) is a correction amount, applicablein the case of occurrence of lateral displacement of the center ofgravity of the operator (rider) (where Pb_err≠0), i.e. in the lean-outor lean-in state, for correcting the desired inverted pendulum masspoint lateral movement amount Pb_diff_y_cmd, determined in the desiredposture state determining section 84, in such a way as to increase thelateral displacement of the center of gravity of the operator (therebyenhancing the lean-out or lean-in state).

Further, in the expression (17a),−K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act) is a feedbackmanipulated variable component having the function of causing thedeviation between the desired value (Pb_diff_y_cmd+Kdstb*Pb_err),obtained by correcting Pb_diff_y_cmd, and the estimated invertedpendulum mass point lateral movement amount Pb_diff_y_act to approachzero, −K2*(Vby_cmd−Vby_act) is a feedback manipulated variable componenthaving the function of causing the deviation (Vby_cmd−Vby_act) toapproach zero, −K3*δf1_cmd_p is a feedback manipulated variablecomponent having the function of causing δf1_cmd to approach zero, and−K4*δf1_dot_cmd_p is a feedback manipulated variable component havingthe function of causing δf1_dot_cmd to approach zero.

Further, of −K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act),−K1*Kdstb*Pb_err is a manipulated variable component having the functionof applying a moment in the direction of further increasing themagnitude of Pb_err (a moment in the roll direction) to the vehicle body2.

In the present embodiment, the moment in the direction of furtherincreasing the magnitude of Pb_err is applied to the vehicle body 2 on arequired condition that the magnitude of Pb_err as the rider'scenter-of-gravity lateral displacement index value is a predeterminedvalue or greater.

Therefore, in the case where the magnitude (absolute value) of Pb_err issmaller than the predetermined value (in the case where Pb_err takes avalue in the dead band near zero), the posture control arithmeticsection 85 performs the computation of the above expression (17a) bysetting Kdstb*Pb_err=0.

In the above-described manner, the posture control arithmetic section 85performs the arithmetic processing of the above expressions (17a) to(17c), at each control processing cycle, to thereby calculate δf1_cmd,δf1_dot_cmd, and δf1_dot2_cmd.

Supplementally, δf1_cmd_p and δf1_dot_cmd_p used in the computation ofthe expression (17a) have the meanings as pseudo estimates (alternativeobserved values) of the actual first steering angle and first steeringangular velocity, respectively, at the present time. Therefore, insteadof δf1_cmd_p, a detected first steering angle δf1_act at the presenttime may be used. Further, instead of δf1_dot_cmd_p, a detected firststeering angular velocity δf1_dot_act based on an output from theaforesaid first steering angle detector 62 may be used.

Next, the control device 60 carries out the processing in the secondsteering angle command determining section 86. As shown in FIG. 16, thesecond steering angle command determining section 86 receives: a desiredfirst steering angle δf1_cmd determined in the posture controlarithmetic section 85, and a detected value Th_act (hereinafter,referred to as “detected handlebar torque Th_act”) of a handlebar torqueTh indicated by an output from the aforesaid handlebar torque detector64.

The second steering angle command determining section 86 uses theseinput values to perform the arithmetic processing shown by the block andline diagram in FIG. 16, to determine a desired second steering angleδf2_cmd, a desired second steering angular velocity δf2_dot_cmd, and adesired second steering angular acceleration δf2_dot2_cmd.

That is, the second steering angle command determining section 86calculates the desired second steering angle δf2_cmd by the arithmeticprocessing of the following expressions (18a) to (18e). Further, thesecond steering angle command determining section 86 differentiates thedesired second steering angle δf2_cmd, as shown by the followingexpression (18f), to calculate the desired second steering angularvelocity δf2_dot_cmd. Further, the second steering angle commanddetermining section 86 differentiates the desired second steeringangular velocity δf2_dot_cmd, as shown by the following expression(18g), to calculate the desired second steering angular accelerationδf2_dot2_cmd.δf2_dot2_1=K5*Th_act−K5*δf2_dot_1_p−K6*δf2_1_p  (18a)δf2_dot_1=integral of δf2_dot2_1  (18b)δf2_1=integral of δf2_dot_1  (18c)δf2_2=Rt*δf1_cmd  (18d)δf2_cmd=δf2_1−δf2_2  (18e)δf2_dot_cmd=differential (temporal change rate) of δf2_cmd  (18f)δf2_dot2_cmd=differential (temporal change rate) of δf2_dot_cmd  (18g)

In FIG. 16, a processing section 86-1 represents a processing sectionwhich perform the arithmetic processing of the expressions (18a), (18b),and (18c), and processing sections 86-2, 86-3, 86-4, and 86-5 representprocessing sections which perform the arithmetic processing of theexpressions (18d), (18e), (18f), and (18g), respectively.

Here, δf2_dot2_1 calculated by the expression (18a) is a required valueof the steering angular acceleration (of the front wheel 3 f about thesecond steering axis Cf2) according to the handlebar torque Th that isapplied about the second steering axis Cf2 by the operator'smanipulation of the handlebar 46.

In this case, Kh, K5, and K6 used in the arithmetic processing of theexpression (18a) are gains of predetermined values. The values of thesegains Kh, K5, and K6 are set variably in accordance with, for example,the traveling speed Vox_act of the two-wheeled vehicle 1, or thedetected first steering angle δf1_act and the detected second steeringangle δf2_act.

Further. δf2_dot_1_p in the expression (18a) is a value (last time'svalue) of the steering angular velocity δf2_dot_1 that was calculated bythe expression (18b) in the last time's control processing cycle, andδf2_1_p is a value (last time's value) of the steering angle δf2_1 thatwas calculated by the expression (18c) in the last time's controlprocessing cycle.

The first term on the right side of the expression (18a) is afeedforward manipulated variable according to the detected handlebartorque Th_act, the second term on the right side is a feedbackmanipulated variable for making the steering angular velocity δf2_dot_1approach zero, and the third term on the right side is a feedbackmanipulated variable for making the steering angle δf2_1 approach zero.

f2_1, which is calculated by performing integration twice by theexpressions (18b) and (18c) on δf2_dot2_1 calculated by the expression(18a), is a basic value of the desired second steering angle δf2_cmd.

Further, δf2_2 calculated by the expression (18d) is a steering anglecorrection amount for correcting the basic value δf2_1 in accordancewith the desired first steering angle δf1_cmd. Rt in the expression(18d) is a coefficient for defining the ratio of the steering anglecorrection amount δf2_2 to the desired first steering angle δf1_cmd. Thevalue of the coefficient Rt is set to a fixed value, or set variably inaccordance with the traveling speed Vox_act of the two-wheeled vehicle1.

As the steering angle correction amount δf2_2 calculated by theexpression (18d) is subtracted from the basic value δf2_1 of the desiredsecond steering angle δf2_cmd, the basic value δf2_1 is corrected(expression (18e)). The desired second steering angle δf2_cmd is thusdetermined. Further, the desired second steering angular velocityδf2_dot_cmd and the desired second steering angular accelerationδf2_dot2_cmd are determined from this desired second steering angleδf2_cmd, by the differential operations (expressions (18f) and (18g)).

In the above-described manner, the second steering angle commanddetermining section 86 performs the arithmetic processing of the aboveexpressions (18a) to (18g), at each control processing cycle, to therebycalculate δf2_cmd, δf2_dot_cmd, and δf2_dot2_cmd.

The control device 60 further carries out the processing in the desiredtraveling speed determining section 87. As shown in FIG. 17, the desiredtraveling speed determining section 87 receives a detected value of theactual accelerator manipulated variable indicated by an output from theaforesaid accelerator manipulation detector 66.

The desired traveling speed determining section 87 determines a desiredtraveling speed Vox_cmd from the detected value of the acceleratormanipulated variable by a preset conversion function.

This conversion function is configured, for example, by a mapping or anarithmetic expression. This conversion function is set such that Vox_cmdincreases monotonically with increasing accelerator manipulatedvariable, as illustrated by the graph in FIG. 17, for example.

In the example shown in FIG. 17, Vox_cmd is kept at its maximum valuewhen the detected value of the accelerator manipulated variable is A1 orgreater.

Supplementally, the pattern of increase of Vox_cmd with respect to theincrease of the accelerator manipulated variable may differ from thatshown in FIG. 17.

A description will now be made about the control of the aforesaid firststeering actuator 15, second steering actuator 37, and front-wheeldriving actuator 7.

The control device 60 further includes, as functions other than thoseshown in FIG. 8, an n-th steering actuator control section 91 (where n=1or 2), shown in FIG. 18, and a front-wheel driving actuator controlsection 92, shown in FIG. 19.

It should be noted that the control processing for the first steeringactuator 15 and the second steering actuator 37 are the same. Thus, inFIG. 18, the functional sections controlling the first steering actuator15 and the second steering actuator 37 are collectively referred to asthe n-th steering actuator control section 91. In this case, n=1 for thecontrol of the first steering actuator 15, and n=2 for the control ofthe second steering actuator 37.

The n-th steering actuator control section 91 performs drive control ofthe n-th steering actuator 15 or 37, through the control processingshown by the block and line diagram in FIG. 18, to cause the n-thsteering angle (detected n-th steering angle δfn_act) of the front wheel3 f to track a desired n-th steering angle δfn_cmd.

In this example, the n-th steering actuator control section 91 receives:a desired n-th steering angle δfn_cmd, a desired n-th steering angularvelocity δfn_dot_cmd, and a desired n-th steering angular accelerationδfn_dot2_cmd determined in the posture control arithmetic section 85 orthe second steering angle command determining section 86 in theabove-described manner, a detected n-th steering angle δfn_act, and adetected n-th steering angular velocity δfn_dot_act (detected value ofthe steering angular velocity of the front wheel 3 f about the n-thsteering axis Cfn).

It should be noted that the detected n-th steering angular velocityδfn_dot_act is a value of the steering angular velocity that isrecognized on the basis of an output from the n-th steering angledetector 62 or 63, or a value calculated as a differential (temporalchange rate) of the detected n-th steering angle &fn_act.

The n-th steering actuator control section 91 determines an electriccurrent command value I_δfn_cmd, which is a desired value of theelectric current passed through the n-th steering actuator 15 or 37(electric motor), from the above-described input values by thearithmetic processing in an electric current command value determiningsection 91-1.

This electric current command value determining section 91-1 determinesthe electric current command value I_δfn_cmd by summing up: a feedbackmanipulated variable component obtained by multiplying the deviationbetween δfn_cmd and δfn_act by a gain Kδfn_p of a predetermined value, afeedback manipulated variable component obtained by multiplying thedeviation between δfn_dot_cmd and δfn_dot_act by a gain Kδfn_v of apredetermined value, and a feedforward manipulated variable componentobtained by multiplying δfn_dot2_cmd by a gain Kδfn_a of a predeterminedvalue, as shown by the following expression (19).I_δfn_cmd=Kδfn_p*(δfn_cmd−δfn_act)+Kδfn_v*(δfn_dot_cmd−δfn_dot_act)+Kδfn_a*δfn_dot2_cmd  (19)

The n-th steering actuator control section 91 then performs control, byan electric current control section 91-2 configured with a motor driveror the like, to cause the electric current actually passed through then-th steering actuator 15 or 37 to match the electric current commandvalue I_fn_cmd.

Accordingly, control is performed such that the actual steering angle ofthe front wheel 3 f about the n-th steering axis Cfn tracks the desiredn-th steering angle δfn_cmd.

It should be noted that the technique of controlling the n-th steeringactuator 15 or 37 to cause the actual steering angle of the front wheel3 f about the n-th steering axis Cfn to track the desired n-th steeringangle δfn_cmd is not limited to the above-described technique; othertechniques may be used as well. For example, various kinds of knownservo control techniques related to electric motors (feedback controltechniques for causing the actual angle of rotation of the rotor of theelectric motor to track a desired value) may be adopted.

Next, the front-wheel driving actuator control section 92 performs drivecontrol of the front-wheel driving actuator 7, through for example thecontrol processing shown by the block and line diagram in FIG. 19, tocause the actual rotational transfer velocity of the front wheel 3 f totrack a desired traveling speed Vox_cmd (or to cause the actualrotational angular velocity of the front wheel 3 f to track a desiredrotational angular velocity corresponding to Vox_cmd).

In this example, the front-wheel driving actuator control section 92receives: a desired traveling speed Vox_cmd determined in the desiredtraveling speed determining section 87 in the above-described manner,and an estimated traveling speed Vox_act calculated by the aboveexpression (13e).

The front-wheel driving actuator control section 92 determines anelectric current command value I_Vf_cmd, which is a desired value of theelectric current passed through the front-wheel driving actuator 7(electric motor), from the above-described input values by theprocessing in an electric current command value determining section92-1.

This electric current command value determining section 92-1 determines,as the electric current command value I_Vf_cmd, a feedback manipulatedvariable component obtained by multiplying the deviation between Vox_cmdand Vox_act by a gain KVf_v of a predetermined value, as shown by thefollowing expression (20).I_Vf_cmd=KVf_v*(Vox_cmd−Vox_act)  (20)

It should be noted that, instead of determining I_Vf_cmd by the aboveexpression (20), it may be possible to determine I_Vf_cmd by, forexample, multiplying the deviation between a value Vf_cmd, obtained bydividing Vox_cmd by cos(δf_act) (i.e. a desired value of the rotationaltransfer velocity of the front wheel 3 f), and the estimated front-wheelrotational transfer velocity Vf_act by a gain of a predetermined value.Alternatively, it may be possible to determine I_Vf_cmd by multiplyingthe deviation between a value obtained by dividing Vf_cmd by theeffective rolling radius of the front wheel 3 f (i.e. a desired value ofthe rotational angular velocity of the front wheel 3 f) and the detectedvalue of the actual rotational angular velocity of the front wheel 3 f,indicated by an output from the front-wheel rotational speed detector65, by a gain of a predetermined value.

The front-wheel driving actuator control section 92 then performscontrol, by an electric current control section 92-2 configured with amotor driver or the like, to cause the electric current actually passedthrough the front-wheel driving actuator 7 to match the electric currentcommand value I_Vf_cmd.

Accordingly, control is performed such that the actual rotationaltransfer velocity of the front wheel 3 f tracks Vf_cmd (or the actualrotational angular velocity tracks a desired value of the rotationalangular velocity corresponding to Vf_cmd) and, hence, that the actualtraveling speed tracks the desired traveling speed Vox_cmd.

It should be noted that the technique of controlling the front-wheeldriving actuator 7 to cause the traveling speed of the two-wheeledvehicle 1 or the rotational transfer velocity of the front wheel 3 f totrack the desired value is not limited to the above-described technique;other techniques may be used as well. For example, various kinds ofknown speed control techniques related to electric motors (feedbackcontrol techniques for causing the actual rotational angular velocity ofthe rotor of the electric motor to track a desired value) may beadopted.

The above has described the details of the control processing in thecontrol device 60 according to the present embodiment.

Here, the correspondence between the present embodiment and the presentinvention will be described supplementally.

In the present embodiment, the first steering actuator 15 and the secondsteering actuator 37 correspond to the actuator in the presentinvention. In this case, they have the function as an actuator whichmoves the center of gravity of the vehicle body 2 in the lateraldirection (Y-axis direction) so as to cause a moment in the rolldirection to act on the vehicle body 2 by the gravitational force actingon the vehicle body 2.

In this case, the first steering actuator 15 is able to move the centerof gravity of the vehicle body 2 in the lateral direction (Y-axisdirection), without causing the ground contact point of the front wheel3 f (steered wheel) to move in the lateral direction (Y-axis direction).

Further, the second steering actuator 37 primarily has the function asan actuator which steers the front wheel 3 f so as to cause the groundcontact point of the front wheel 3 f (steered wheel) to move in thelateral direction (Y-axis direction).

It should be noted that in the state where the second steering angle δf2of the front wheel 3 f is kept constant by the second steering actuator37, the first steering actuator 15 has the function as the actuatorwhich steers the front wheel 3 f so as to cause the ground contact pointof the front wheel 3 f (steered wheel) to move in the lateral direction.

The first steering actuator 15 also has the function as the actuatorwhich moves the center of gravity of the vehicle body 2 in the lateraldirection (Y-axis direction).

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 83 corresponds to the center-of-gravity displacementdegree index value determining section in the present invention. In thiscase, the estimated inverted pendulum mass point lateral displacementPb_err corresponds to the center-of-gravity displacement degree indexvalue in the present invention. Further, the position on the plane ofsymmetry of the vehicle body 2 corresponds to the predeterminedreference position related to the position of the center of gravity ofthe operator.

Further, the estimated front-wheel rotational transfer velocity Vf_act,the detected first steering angle δf1_act, the detected second steeringangle δf2_act, and the second estimated inverted pendulum mass pointlateral velocity Pb_diff_dot_y_2 as a differential of the estimatedinverted pendulum mass point lateral movement amount Pb_diff_y_actcorrespond to the observed values of the motional state of the mobilebody (two-wheeled vehicle 1) used in the processing of thecenter-of-gravity displacement degree index value determining section(rider's center-of-gravity lateral displacement index value calculatingsection 83). In this case, Pb_diff_dot_y_2 corresponds to the observedvalue of the inclination state quantity of the vehicle body 2.

Further, the above expressions (12a) and (12b) correspond to thedynamics computation in the present invention. The first estimatedinverted pendulum mass point lateral velocity Pb_diff_dot_y_1 calculatedby the expression (12b) corresponds to the calculated value of theinclination state quantity of the vehicle body 2.

Furthermore, the posture control arithmetic section 85 corresponds tothe control input determining section in the present invention, andδf1_dot2_cmd calculated by the posture control arithmetic section 85corresponds to the control input in the present invention. The gainKdstb in the above expression (17a) performed by the posture controlarithmetic section 85 corresponds to the sensitivity of the change incontrol input (δf1_dot2_cmd) to the change in center-of-gravitydisplacement degree index value (estimated inverted pendulum mass pointlateral displacement Pb_err).

According to the first embodiment described above, in the state wherethe center of gravity of the operator is located on the plane ofsymmetry of the vehicle body 2 (i.e. in the reference position) or inthe state close thereto (including the state where the absolute value ofPb_err is smaller than a predetermined value), the front wheel 3 f issteered via the first steering actuator 15 and the second steeringactuator 37 in such a way as to suppress divergence of the estimatedinverted pendulum mass point lateral movement amount Pb_diff_y_act froma desired inverted pendulum mass point lateral movement amountPb_diff_y_cmd.

In the case where the center of gravity of the operator has beendisplaced laterally from the reference position to a lean-in or lean-outstate (specifically, upon occurrence of lateral displacement causing anabsolute value Pb_err to be the predetermined value or greater), thefront wheel 3 f is steered via the first steering actuator 15 in such amanner that a momentin the direction of further increasing the lateraldisplacement (a moment in the roll direction) is applied to the vehiclebody 2. As a result, it becomes readily possible for an operator toquickly realize a lean-in or lean-out state when the operator shiftshis/her weight in an attempt to achieve the lean-in or lean-out state.It is therefore possible to improve the maneuverability of thetwo-wheeled vehicle 1 at the time of turning.

Second Embodiment

A second embodiment of the present invention will be described belowwith reference to FIGS. 20 to 22. The mobile body in the presentembodiment is the same as the mobile body (two-wheeled vehicle 1) in thefirst embodiment. The present embodiment differs from the firstembodiment only in part of the control processing of the control device.Therefore, the description of the present embodiment will focus on thematters different from the first embodiment. Detailed descriptions ofthe matters identical to those in the first embodiment will be omitted.

Referring to FIG. 20, in the present embodiment, the control device 60includes, instead of the estimated inverted pendulum mass point lateralvelocity calculating section 82 in the first embodiment, an estimatedinverted pendulum mass point lateral velocity calculating section 100which calculates, as an estimated inverted pendulum mass point lateralvelocity, a differential (temporal change rate) Pb_diff_dot_y_act of anestimated inverted pendulum mass point lateral movement amountPb_diff_y_act.

Further, in the present embodiment, the control device 60 includes,instead of the desired posture state determining section 84 in the firstembodiment, a desired posture state determining section 101 whichdetermines a desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd and a desired inverted pendulum mass point lateralvelocity Pb_diff_dot_y_cmd as a desired value for Pb_diff_dot_y_act.

Further, in the present embodiment, the control device 60 includes,instead of the posture control arithmetic section 85 in the firstembodiment, a posture control arithmetic section 102 and a firststeering angle command determining section 103. The posture controlarithmetic section 102 determines, as a manipulated variable (controlinput) for controlling the posture (inclination angle) in the rolldirection of the vehicle body 2 of the two-wheeled vehicle 1, a desiredposture manipulation moment Msum_cmd which is a desired value of themoment in the roll direction to be acted on the vehicle body 2. Thefirst steering angle command determining section 103 determines, fromthe desired posture manipulation moment Msum_cmd, a desired firststeering angular acceleration δf1_dot2_cmd, a desired first steeringangular velocity δf1_dot_cmd, and a desired first steering angleδf1_cmd.

The functions of the control device 60 other than the estimated invertedpendulum mass point lateral velocity calculating section 100, thedesired posture state determining section 101, the posture controlarithmetic section 102, and the first steering angle command determiningsection 103 are the same as in the first embodiment.

The desired posture state determining section 101 determines the desiredinverted pendulum mass point lateral movement amount Pb_diff_y_cmd in asimilar manner as in the first embodiment. The desired posture statedetermining section 101 sets the desired inverted pendulum mass pointlateral velocity Pb_diff_dot_y_cmd to zero, for example. The desiredinverted pendulum mass point lateral velocity Pb_diff_dot_y_cmd,however, may be determined variably in accordance with, for example, thedetected first steering angle δf1_act and the detected second steeringangle δf2_act.

Further, the desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd may be set to zero, for example. Alternatively, thedesired inverted pendulum mass point lateral movement amountPb_diff_y_cmd may be determined variably in accordance with, forexample, the detected first steering angle δf1_act and the detectedsecond steering angle δf2_act.

The posture control arithmetic section 102 receives: an estimatedinverted pendulum mass point lateral movement amount Pb_diff_y_act, anestimated inverted pendulum mass point lateral velocityPb_diff_dot_y_act as a differential of Pb_diff_y_act, a desired invertedpendulum mass point lateral movement amount Pb_diff_y_cmd, a desiredinverted pendulum mass point lateral velocity Pb_diff_dot_y_cmd, and anestimated inverted pendulum mass point lateral displacement Pb_err.

In this case, Pb_diff_y_act, Pb_diff_y_cmd, and Pb_err are the same asthose explained above in the first embodiment. On the other hand,Pb_diff_dot_y_act and Pb_diff_dot_y_cmd are the values determined in theestimated inverted pendulum mass point lateral velocity calculatingsection 100 and the desired posture state determining section 101,respectively, in the present embodiment.

The posture control arithmetic section 102 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 21, to determine a desired posture manipulation moment Msum_cmd.

That is, the posture control arithmetic section 102 calculates thedesired posture manipulation moment Msum_cmd by the arithmeticprocessing of the following expression (21).Msum_cmd=−K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act)−K2*(Pb_diff_dot_y_cmd−Pb_diff_dot_y_act)  (21)

Here, Kdstb, K1, and K2 in the expression (21) are gains ofpredetermined values. The values of these gains Kdstb, K1, and K2 areset variably in accordance with, for example, the estimated travelingspeed Vox_act of the two-wheeled vehicle 1, or the detected firststeering angle δf1_act and the detected second steering angle δf2_act,as in the first embodiment.

In this case, in the present embodiment, the values of the gains Kdstb,K1, and K2 are set such that the moment in the roll direction acting onthe vehicle body 2 by the steering of the front wheel 3 f according toδf1_dot2_cmd, δf1_dot_cmd, and δf1_cmd will become not so large (suchthat the operator can lean the vehicle body 2 in the roll directionrelatively easily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb, K1, and K2 are all setvariably such that they become smaller as the estimated traveling speedVox_act of the two-wheeled vehicle 1 is higher.

In the expression (21), −K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act)is a feedback manipulated variable component having the function ofcausing the deviation between a desired value(Pb_diff_y_cmd+Kdstb*Pb_err), obtained by correcting Pb_diff_y_cmdaccording to Pb_err, and Pb_diff_y_act to approach zero, and−K2*(Pb_diff_dot_y_cmd−Pb_diff_dot_y_act) is a feedback manipulatedvariable component having the function of causing the deviation(Pb_diff_dot_y_cmd−Pb_diff_dot_y_act) to approach zero.

Further, of −K1*((Pb_diff_y_cmd+Kdstb*Pb_err)−Pb_diff_y_act),−K1*Kdstb*Pb_err is a manipulated variable component having the functionof applying a moment in the direction of further increasing themagnitude of Pb_err (a moment in the roll direction) to the vehicle body2.

It should be noted that in the present embodiment, in the case where themagnitude (absolute value) of Pb_err is smaller than a predeterminedvalue (in the case where Pb_err takes a value in the dead band nearzero), the posture control arithmetic section 102 performs thecomputation of the above expression (21) by setting Kdstb*Pb_err=0, asin the case of the first embodiment. Therefore, the moment in thedirection of further increasing the magnitude of Pb_err is applied tothe vehicle body 2 on the condition that the magnitude of Pb_err is thepredetermined value or greater.

In the above-described manner, in the present embodiment, the posturecontrol arithmetic section 102 performs the arithmetic processing of theexpression (21), at each control processing cycle, to thereby calculatethe desired posture manipulation moment Msum_cmd.

Here, the reasons why Pb_diff_dot_y_cmd and Pb_diff_dot_y_act are usedinstead of Vby_cmd and Vby_act in the arithmetic processing in theposture control arithmetic section 102 in the present embodiment will bedescribed supplementally.

In the first embodiment described above, the desired first steeringangular acceleration δf1_dot2_cmd is used as a basic control input formanipulation of the posture of the vehicle body 2 (for manipulation ofthe inverted pendulum mass point lateral movement amount Pb_diff_y). Inthis case, the state equation regarding the posture control of thevehicle body 2 is expressed by the following expression (22).

$\begin{matrix}{{\frac{d}{dt}\begin{pmatrix}{{Pb\_ diff}{\_ y}} \\{Vby} \\{\delta\; f\; 1} \\{\delta\;{f1\_ dot}}\end{pmatrix}} = {{\begin{pmatrix}0 & 1 & {{- {Vox}} \cdot \frac{Lr}{L} \cdot {\cos\left( {\theta\mspace{14mu}{cs}} \right)}} & 0 \\\frac{g}{h^{\prime}} & 0 & {- {f\left( {{\delta\; f\; 1},{Vox}} \right)}} & 0 \\0 & 0 & 0 & 1 \\0 & 0 & 0 & 0\end{pmatrix} \cdot \begin{pmatrix}{{Pb\_ diff}{\_ y}} \\{Vby} \\{\delta\; f\; 1} \\{\delta f1\_ dot}\end{pmatrix}} + {{\begin{pmatrix}0 \\0 \\0 \\1\end{pmatrix} \cdot {\delta f1\_ dot2}}{\_ cmd}}}} & (22)\end{matrix}$

It should be noted that f(δf1,Vox) represents a function of the firststeering angle δf1 and the traveling speed Vox of the two-wheeledvehicle 1.

Therefore, the controlled state quantities become four parameters ofPb_diff_y, Vby, δf1, and δf1_dot.

On the other hand, in the second embodiment, the desired posturemanipulation moment Msum_cmd as a desired value of the moment in theroll direction is used as a basic control input for manipulation of theposture of the vehicle body 2 (for manipulation of the inverted pendulummass point lateral movement amount Pb_diff_y). In this case, the stateequation regarding the posture control of the vehicle body 2 isexpressed by the following expression (23).

$\begin{matrix}{{\frac{d}{dt}\begin{pmatrix}{{Pb\_ diff}{\_ y}} \\{{Pb\_ diff}{\_ dot}{\_ y}}\end{pmatrix}} = {{\begin{pmatrix}0 & 1 \\\frac{g}{h^{\prime}} & 0\end{pmatrix} \cdot \begin{pmatrix}{{Pb\_ diff}{\_ y}} \\{{Pb\_ diff}{\_ dot}{\_ y}}\end{pmatrix}} + {\begin{pmatrix}0 \\{- \frac{1}{m\;{1 \cdot h^{\prime}}}}\end{pmatrix} \cdot {Msum\_ cmd}}}} & (23)\end{matrix}$

Therefore, the controlled state quantities become two parameters ofPb_diff_y and Pb_diff_dot_y. Accordingly, in the present embodiment,Pb_diff_dot_y_cmd and Pb_diff_dot_y_act are used instead of Vby_cmd andVby_act in the arithmetic processing in the posture control arithmeticsection 102.

Next, the first steering angle command determining section 103 receivesa desired posture manipulation moment Msum_cmd determined in the posturecontrol arithmetic section 102. The first steering angle commanddetermining section 103 uses the input value of Msum_cmd to perform thearithmetic processing shown by the block and line diagram in FIG. 22, todetermine a desired first steering angle δf1_cmd, a desired firststeering angular velocity δf1_dot_cmd, and a desired first steeringangular acceleration δf1_dot2_cmd.

That is, the first steering angle command determining section 103determines δf1_cmd, δf1_dot_cmd, and δf1_dot2_cmd by the arithmeticprocessing of the following expressions (24a), (24b), and (24c).δf1_cmd=f1(Msum_cmd)  (24a)δf1_dot_cmd=differential (temporal change rate) of δf1_cmd  (24b)δf1_dot2_cmd=differential (temporal change rate) of δf1_dot_cmd  (24c)

In FIG. 22, processing sections 103-1, 103-2, and 103-3 representprocessing sections which perform the arithmetic processing of theexpressions (24a), (24b), and (24c), respectively.

Here, f1(Msum_cmd) in the expression (24a) is a function value which isdetermined by a preset conversion function f1(Msum) from the value ofMsum_cmd in the processing section 103-1 in FIG. 22. Therefore, by theconversion function f1(Msum). Msum_cmd is converted into δf1_cmd as afunction value thereof.

The conversion function f1(Msum) is configured, for example, by amapping or an arithmetic expression. In the present embodiment, theconversion function f1(Msum) has been set, as illustrated by the graphin the processing section 103-1, such that the value of f1 (=value ofδf1_cmd) increases monotonically from a value on the negative side to avalue on the positive side as the value of Msum increases (from a valueon the negative side to a value on the positive side).

In the above-described manner, the first steering angle commanddetermining section 103 performs the arithmetic processing of the aboveexpressions (24a) to (24c), at each control processing cycle, to therebycalculate δf1_cmd, δf1_dot_cmd, and δf1_dot2_cmd.

The present embodiment is identical to the first embodiment except forthe matters described above.

Here, the correspondence between the present embodiment and the presentinvention will be described supplementally. The posture controlarithmetic section 102 corresponds to the control input determiningsection in the present invention, and Msum_cmd calculated by the posturecontrol arithmetic section 102 corresponds to the control input in thepresent invention. The gain Kdstb in the above expression (21) performedby the posture control arithmetic section 102 corresponds to thesensitivity of the change in control input (Msum_cmd) to the change incenter-of-gravity displacement degree index value (estimated invertedpendulum mass point lateral displacement Pb_err).

Otherwise, the correspondence between the present embodiment and thepresent invention is identical to that in the first embodiment.

According to the second embodiment described above, it is possible toachieve the effects similar to those in the first embodiment.

Third Embodiment

A third embodiment of the present invention will now be described withreference to FIGS. 23 to 25. The mobile body in the present embodimentis the same as the mobile body (two-wheeled vehicle 1) in the firstembodiment. The present embodiment differs from the first embodimentonly in part of the control processing of the control device. Therefore,the description of the present embodiment will focus on the mattersdifferent from the first embodiment. Detailed descriptions of thematters identical to those in the first embodiment will be omitted.

In the first embodiment described above, the inverted pendulum masspoint lateral movement amount Pb_diff_y and the inverted pendulum masspoint lateral velocity Vby for the inverted pendulum mass point 71 inthe two-mass-point model were used as the controlled state quantities.

In contrast, in the present embodiment, the roll angle ϕb of the vehiclebody 2 and its temporal change rate, or, the roll angular velocityϕb_dot are used as the controlled state quantities.

Described below more specifically, the control device 60 in the presentembodiment includes, as functions implemented when the CPU executesinstalled programs (functions implemented by software) or as functionsimplemented by hardware configurations, the functions shown by the blockdiagram in FIG. 23.

That is, the control device 60 includes: a roll angular velocitydetecting section 110 which calculates a differential (temporal changerate) of the detected roll angle ϕb_act of the vehicle body 2 as adetected value ϕb_dot_act (hereinafter, referred to as “detected rollangular velocity ϕb_dot_act”) of the roll angular velocity ϕb_dot, arider's center-of-gravity lateral displacement index value calculatingsection 111 which calculates, as the aforesaid rider's center-of-gravitylateral displacement index value, an estimate ϕb_err (hereinafter,referred to as “estimated vehicle body inclination angle displacementϕb_err”) of the deviation between an estimate of the roll angle ϕb ofthe vehicle body 2 when the vehicle body 2 is leaned in the rolldirection to cause the operator's center of gravity to be placed on theplane of symmetry of the vehicle body 2 and the detected roll angleϕb_act as a value of the actual roll angle ϕb, and a desired posturestate determining section 112 which determines a desired value ϕb_cmd(hereinafter, referred to as “desired roll angle ϕb_cmd”) of the rollangle ϕb of the vehicle body 2 and a desired value ϕb_dot_cmd(hereinafter, referred to as “desired roll angular velocity ϕb_dot_cmd”)of the roll angular velocity ϕb_dot.

The control device 60 further includes: a posture control arithmeticsection 113 which determines a desired first steering angle δf1_cmd, adesired first steering angular velocity δf1_dot_cmd, and a desired firststeering angular acceleration δf1_dot2_cmd as primary control inputs(manipulated variables) for controlling the posture in the rolldirection of the vehicle body 2, a second steering angle commanddetermining section 86 which determines a desired second steering angleδf2_cmd, a desired second steering angular velocity δf2_dot_cmd, and adesired second steering angular acceleration δf2_dot2_cmd, and a desiredtraveling speed determining section 87 which determines a desiredtraveling speed Vox_cmd. The second steering angle command determiningsection 86 and the desired traveling speed determining section 87 areidentical to those in the first embodiment.

In the present embodiment, the processing in the rider'scenter-of-gravity lateral displacement index value calculating section111, the desired posture state determining section 112, and the posturecontrol arithmetic section 113 are carried out, at each controlprocessing cycle, in the following manner.

First, the desired posture state determining section 112 determines, asthe desired roll angle ϕb_cmd, a roll angle ϕb_lean which is calculatedby the expression (16a) explained above in conjunction with the firstembodiment, for example. The section 112 sets the desired roll angularvelocity ϕb_dot_cmd to zero, for example. It should be noted that thedesired roll angular velocity ϕb_dot_cmd may be determined variably inaccordance with, for example, the detected first steering angle δf1_actand the detected second steering angle δf2_act.

Further, the desired roll angle ϕb_cmd may be set to zero, for example.Alternatively, the desired roll angle ϕb_cmd may be determined variablyin accordance with, for example, the detected first steering angleδf1_act and the detected second steering angle δf2_act.

As shown in FIG. 24, the rider's center-of-gravity lateral displacementindex value calculating section 111 receives: a detected roll angleϕb_act, a detected first steering angle δf1_act and a detected secondsteering angle δf2_act, and an estimated front-wheel rotational transfervelocity Vf_act.

The rider's center-of-gravity lateral displacement index valuecalculating section 111 calculates an estimated vehicle body inclinationangle displacement ϕb_err as a rider's center-of-gravity lateraldisplacement index value, through the arithmetic processing shown by theblock and line diagram in FIG. 24. In this case, the rider'scenter-of-gravity lateral displacement index value calculating section111 is configured as an observer, as in the first embodiment.

Specifically, the rider's center-of-gravity lateral displacement indexvalue calculating section 111 calculates an estimate of the aforesaidroll moment inertial force component Mi and an estimate of the aforesaidroll moment floor reaction force component Mp by a roll moment inertialforce component calculating section 111-2 and a roll moment floorreaction force component calculating section 111-3, respectively, on thebasis of the input values of δf1_act, δf2_act, and Vf_act.

In this case, the roll moment inertial force component calculatingsection 111-2 calculates an estimate of the roll moment inertial forcecomponent Mi by the arithmetic processing similar to that in the firstembodiment. More specifically, the roll moment inertial force componentcalculating section 111-2 calculates an estimate of Mi by performing thearithmetic processing of the above expressions (13a) to (13e) and thefollowing expression (13f′) which is obtained by replacing m1*h′ on theright side of the above expression (13f) with m*h.Mi=(Voy_dot_act+ωz_act*Vox_act)*m*h  (13f)

Further, the roll moment floor reaction force component calculatingsection 111-3 calculates an estimate of the roll moment floor reactionforce component Mp by performing the arithmetic processing of the aboveexpression (14a), included in the arithmetic processing by the rollmoment floor reaction force component calculating section 83-3 in thefirst embodiment, and the following expression (14d) which is obtainedby setting p2 in the expression (14c) to zero.Mp=Pfy(δf1_act+δf2_act)*(Lr/L)*m*g  (14d)

The rider's center-of-gravity lateral displacement index valuecalculating section 111 then carries out a dynamics computationaccording to the following expression (25a) in a processing section111-4, on the basis of the estimates of Mi and Mp, the input value ofϕb_act, and a value (last time's value) ϕb_err_p of the estimatedvehicle body inclination angle displacement ϕb_err calculated in thelast time's control processing cycle, to thereby calculate an estimateof the roll angular acceleration ϕb_dot2 of the vehicle body 2.

Stated differently, the last time's value ϕb_err_p corresponds to thelatest one of the estimated vehicle body inclination angle displacementsϕb_err calculated up to then.ϕb_dot2=(m*g*h*(ϕb_act+ϕb_err_p)+Mp+Mi)/J  (25a)

In the expression (25a), J is a predetermined, set value of the inertiaof the entirety of the two-wheeled vehicle 1 (including the operator)about the X axis of the aforesaid XYZ coordinate system.

The rider's center-of-gravity lateral displacement index valuecalculating section 111 then integrates, in a processing section 111-5,ϕb_dot2 calculated by the above expression (25a), to thereby calculate afirst estimated roll angular velocity ϕb_dot_1 as a first estimate ofthe roll angular velocity ϕb_dot of the vehicle body 2, as shown by thefollowing expression (25b).ϕb_dot_1=integral of ϕb_dot2  (25b)

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 111 performs a differential operation on the inputvalue of ϕb_act in a processing section 111-1, to thereby calculate asecond estimated roll angular velocity ϕb_dot_2 as a second estimate ofthe roll angular velocity ϕb_dot of the vehicle body 2, as shown by thefollowing expression (25c).ϕb_dot2=differential (temporal change rate) of ϕb_act  (25c)

It should be noted that ϕb_dot_2 calculated by the expression (25c) isthe same as the detected roll angular velocity ϕb_dot_act calculated inthe roll angular velocity detecting section 110. Therefore, the detectedroll angular velocity ϕb_dot_act may be used, without modification, asthe second estimated roll angular velocity ϕb_dot_2.

Here, the first estimated roll angular velocity ϕb_dot_1 calculated bythe above expression (25b) corresponds to the estimate of the roll angleof the vehicle body 2 calculated by assuming that the overall center ofgravity G of the two-wheeled vehicle 1 is located on the plane ofsymmetry of the vehicle body 2.

Therefore, the deviation between the second estimated roll angularvelocity ϕb_dot_2 and the first estimated roll angular velocityϕb_dot_1, calculated dynamically according to the above expressions(25a) and (25b), becomes a value depending on the vehicle bodyinclination angle displacement amount caused by the lateral displacementof the center of gravity of the operator.

Therefore, the rider's center-of-gravity lateral displacement indexvalue calculating section 111 calculates the estimated vehicle bodyinclination angle displacement ϕb_err in a processing section 111-6 bythe arithmetic processing of the following expression (25d).ϕb_err=(ϕb_dot_2−ϕb_dot_1)*Kestm*J/(m*g*h)  (25d)

Kestm used in the arithmetic processing of this expression (25d) is apredetermined gain of a predetermined value. It should be noted thatϕb_err calculated by this expression (25d) takes a negative value whenthe center of gravity of the operator is displaced on the lean-in sidefrom a position on the plane of symmetry of the vehicle body 2, andtakes a positive value when it is displaced on the lean-out side.

Supplementally. Kestm*J/(m*g*h) in the expression (25d) may be set inadvance as a single gain value.

Further, in the block and line diagram in FIG. 24, the last time's value(=ϕb_err_p*m*g*h) of (ϕb_dot_2−ϕb_dot_)*Kestm*J is input to theprocessing section 111-4 from the processing section 111-6. However, thelast time's value ϕb_err_p of the estimated vehicle body inclinationangle displacement ϕb_err, for example, may be directly input to theprocessing section 111-4.

In the above-described manner, the rider's center-of-gravity lateraldisplacement index value calculating section 111 in the presentembodiment calculates the estimates of Mi and Mp, and uses theseestimates and the detected vehicle body roll angle ϕb_act to perform thearithmetic processing of the expressions (25a) to (25d), to therebycalculate the estimated vehicle body inclination angle displacementϕb_err.

Next, as shown in FIG. 25, the posture control arithmetic section 113receives: a desired roll angle ϕb_cmd and a desired roll angularvelocity ϕb_dot_cmd, determined in the desired posture state determiningsection 112, a detected roll angle ϕb_act and a detected roll angularvelocity ϕb_dot_act, and an estimated vehicle body inclination angledisplacement ϕb_err calculated in the rider's center-of-gravity lateraldisplacement index value calculating section 111.

The posture control arithmetic section 113 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 25, to determine a desired first steering angle δf1_cmd, a desiredfirst steering angular velocity δf1_dot_cmd, and a desired firststeering angular acceleration δf1_dot2_cmd.

That is, the posture control arithmetic section 113 calculates thedesired first steering angular acceleration δf1_dot2_cmd by thearithmetic processing of the following expression (26a), which issimilar in form to the above expression (17a) in the first embodiment.Further, the posture control arithmetic section 113 performs integrationoperations on δf1_dot2_cmd, as shown by the following expressions (26b)and (26c), to calculate the desired first steering angular velocityδf1_dot_cmd and the desired first steering angle δf1_cmd. Theexpressions (26b) and (26c) are identical to the above expressions (17b)and (17c), respectively.δf1_dot2_cmd=−K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act)−K2*(ϕb_dot_cmd−ϕb_dot_act)−K3*δf1_cmd_p−K4*f1_dot_cmd_p  (26a)δf1_dot_cmd=integral of δf1_dot2_cmd  (26b)δf1_cmd=integral of f1_dot_cmd  (26c)

In FIG. 25, processing sections 113-1, 113-2, and 113-3 representprocessing sections which perform the arithmetic processing of theexpressions (26a), (26b), and (26c), respectively.

Here, Kdstb, K1, K2, K3, and K4 in the expression (26a) are gains ofpredetermined values. The values of these gains Kdstb, K1, K2, K3, andK4 are set variably in accordance with, for example, the estimatedtraveling speed Vox_act of the two-wheeled vehicle 1, or the detectedfirst steering angle δf1_act and the detected second steering angleδf2_act.

In this case, the values of the gains Kdstb, K1, K2, K3, and K4 are setsuch that the moment in the roll direction acting on the vehicle body 2by the steering of the front wheel 3 f according to δf1_dot2_cmd,δf1_dot_cmd, and δf1_cmd will become not so large (such that theoperator can lean the vehicle body 2 in the roll direction relativelyeasily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb, K1, K2, K3, and K4 are allset such that they vary in accordance with the estimated traveling speedVox_act of the two-wheeled vehicle 1.

For example, the magnitudes of the gains K1, K2, K3, and K4 are all setvariably such that they become smaller as the estimated traveling speedVox_act of the two-wheeled vehicle 1 is higher.

It should be noted that the values of the gains Kdstb, K1, K2, K3, andK4 are generally different from those in the first embodiment.

Kdstb*ϕb_err in the expression (26a) is a correction amount, applicablein the case of occurrence of lateral displacement of the center ofgravity of the operator (rider) (where ϕb_err≠0), i.e. in the lean-outor lean-in state, for correcting the desired roll angle ϕb_cmd,determined in the desired posture state determining section 112, in sucha way as to increase the lateral displacement of the center of gravityof the operator (thereby enhancing the lean-out or lean-in state).

Further, in the expression (26a). −K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act) isa feedback manipulated variable component having the function of causingthe deviation between the desired value (ϕb_cmd+Kdstb*ϕb_err) obtainedby correcting ϕb_cmd and the detected roll angle ϕb_act to approachzero, −K2*(ϕb_dot_cmd−ϕb_dot_act) is a feedback manipulated variablecomponent having the function of causing the deviation(ϕb_dot_cmd−ϕb_dot_act) to approach zero, −K3*δf1_cmd_p is a feedbackmanipulated variable component having the function of causing δf1_cmd toapproach zero, and −K4*δf1_dot_cmd_p is a feedback manipulated variablecomponent having the function of causing δf1_dot_cmd to approach zero.

Further, of −K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act), −K1*Kdstb*ϕb_err is amanipulated variable component having the function of applying a momentin the direction of further increasing the magnitude of ϕb_err (a momentin the roll direction) to the vehicle body 2.

In the present embodiment, in the case where the magnitude (absolutevalue) of ϕb_err as the rider's center-of-gravity lateral displacementindex value is smaller than a predetermined value (in the case whereϕb_err takes a value in the dead band near zero), the posture controlarithmetic section 113 performs the computation of the above expression(26a) by setting Kdstb*ϕb_err=0. Therefore, the moment in the directionof further increasing the magnitude of ϕb_err is applied to the vehiclebody 2 on the condition that the magnitude of ϕb_err is thepredetermined value or greater.

In the above-described manner, the posture control arithmetic section113 performs the arithmetic processing of the above expressions (26a) to(26c), at each control processing cycle, to thereby calculate δf1_cmd,δf1_dot_cmd, and δf1_dot2_cmd.

The present embodiment is identical to the first embodiment except forthe matters described above.

Here, the correspondence between the present embodiment and the presentinvention will be described supplementally.

In the present embodiment, the first steering actuator 15 and the secondsteering actuator 37 correspond to the actuator in the presentinvention. In this case, they have the function as an actuator whichmoves the center of gravity of the vehicle body 2 in the lateraldirection (Y-axis direction) so as to cause a moment in the rolldirection to act on the vehicle body 2 by the gravitational force actingon the vehicle body 2.

In this case, the first steering actuator 15 is able to move the centerof gravity of the vehicle body 2 in the lateral direction (Y-axisdirection), without causing the ground contact point of the front wheel3 f (steered wheel) to move in the lateral direction (Y-axis direction).

Further, the second steering actuator 37 primarily has the function asan actuator which steers the front wheel 3 f so as to cause the groundcontact point of the front wheel 3 f (steered wheel) to move in thelateral direction (Y-axis direction).

It should be noted that in the state where the second steering angle δf2of the front wheel 3 f is kept constant by the second steering actuator37, the first steering actuator 15 has the function as the actuatorwhich steers the front wheel 3 f so as to cause the ground contact pointof the front wheel 3 f (steered wheel) to move in the lateral direction.

The first steering actuator 15 also has the function as the actuatorwhich moves the center of gravity of the vehicle body 2 in the lateraldirection (Y-axis direction).

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 111 corresponds to the center-of-gravitydisplacement degree index value determining section in the presentinvention. In this case, the estimated vehicle body inclination angledisplacement ϕb_err corresponds to the center-of-gravity displacementdegree index value in the present invention. Further, the position onthe plane of symmetry of the vehicle body 2 corresponds to thepredetermined reference position related to the position of the centerof gravity of the operator.

Further, the estimated front-wheel rotational transfer velocity Vf_act,the detected first steering angle δf1_act, the detected second steeringangle δf2_act, and the second estimated roll angular velocity ϕb_dot_2(=detected roll angular velocity ϕb_dot_act) as a differential of thedetected roll angle ϕb_act correspond to the observed values of themotional state of the mobile body (two-wheeled vehicle 1) used in theprocessing of the center-of-gravity displacement degree index valuedetermining section (rider's center-of-gravity lateral displacementindex value calculating section 111). In this case, ϕb_dot_2 correspondsto the observed value of the inclination state quantity of the vehiclebody 2.

Further, the above expressions (25a) and (25b) correspond to thedynamics computation in the present invention. The first estimated rollangular velocity ϕb_dot_1 calculated by the expression (25b) correspondsto the calculated value of the inclination state quantity of the vehiclebody 2.

It should be noted that the dynamics computation in this case becomesthe dynamics computation based on the dynamic model of the system madeup of the mass point of the mass m (mass point of the overall center ofgravity) and the inertia J.

Furthermore, the posture control arithmetic section 113 corresponds tothe control input determining section in the present invention, andδf1_dot2_cmd calculated by the posture control arithmetic section 113corresponds to the control input in the present invention. The gainKdstb in the above expression (26a) performed by the posture controlarithmetic section 113 corresponds to the sensitivity of the change incontrol input (δf1_dot2_cmd) to the change in center-of-gravitydisplacement degree index value (estimated vehicle body inclinationangle displacement ϕb_err).

According to the third embodiment described above, it is possible toachieve the effects similar to those in the first embodiment. The firstor second embodiment, however, is more advantageous than the thirdembodiment in terms of improving the reliability of the posture controlof the vehicle body 2.

Fourth Embodiment

A fourth embodiment of the present invention will be described belowwith reference to FIGS. 26 and 27. The mobile body in the presentembodiment is the same as the mobile body (two-wheeled vehicle 1) in thethird embodiment. The present embodiment differs from the thirdembodiment only in part of the control processing of the control device.Therefore, the description of the present embodiment will focus on thematters different from the third embodiment. Detailed descriptions ofthe matters identical to those in the third embodiment will be omitted.

Referring to FIG. 26, in the present embodiment, the control device 60includes, instead of the posture control arithmetic section 113 in thethird embodiment, a posture control arithmetic section 120 and a firststeering angle command determining section 103. The posture controlarithmetic section 120 determines, as a manipulated variable (controlinput) for controlling the posture (inclination angle) in the rolldirection of the vehicle body 2 of the two-wheeled vehicle 1, a desiredposture manipulation moment Msum_cmd which is a desired value of themoment in the roll direction to be acted on the vehicle body 2. Thefirst steering angle command determining section 103 determines adesired first steering angular acceleration δf1_dot2_cmd, a desiredfirst steering angular velocity δf1_dot_cmd, and a desired firststeering angle δf1_cmd from the desired posture manipulation momentMsum_cmd.

The functions of the control device 60 other than the posture controlarithmetic section 120 and the first steering angle command determiningsection 103 are the same as in the third embodiment.

The posture control arithmetic section 120 receives: a detected rollangle ϕb_act and a detected roll angular velocity ϕb_dot_act of thevehicle body 2, a desired roll angle ϕb_cmd and a desired roll angularvelocity ϕb_dot_cmd determined in the desired posture state determiningsection 112, and an estimated vehicle body inclination angledisplacement ϕb_err calculated in the rider's center-of-gravity lateraldisplacement index value calculating section 111.

The posture control arithmetic section 120 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 27, to determine a desired posture manipulation moment Msum_cmd.

That is, the posture control arithmetic section 120 calculates thedesired posture manipulation moment Msum_cmd by the arithmeticprocessing of the following expression (27).Msum_cmd=−K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act)−K2*(ϕb_dot_cmd−ϕb_dot_act)  (27)

Here, Kdstb, K1, and K2 in the expression (27) are gains ofpredetermined values. The values of these gains Kdstb, K1, and K2 areset variably in accordance with, for example, the estimated travelingspeed Vox_act of the two-wheeled vehicle 1, or the detected firststeering angle δf1_act and the detected second steering angle δf2_act,as in the third embodiment.

In this case, the values of the gains Kdstb, K1, and K2 are set suchthat the moment in the roll direction acting on the vehicle body 2 bythe steering of the front wheel 3 f according to Msum_cmd will becomenot so large (such that the operator can lean the vehicle body 2 in theroll direction relatively easily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb, K1, and K2 are all set suchthat they vary in accordance with the estimated traveling speed Vox_actof the two-wheeled vehicle 1.

For example, the magnitudes of the gains K1 and K2 are both set variablysuch that they become smaller as the estimated traveling speed Vox_actof the two-wheeled vehicle 1 is higher.

In the expression (27), −K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act) is a feedbackmanipulated variable component having the function of causing thedeviation between the desired value (ϕb_cmd+Kdstb*ϕb_err), obtained bycorrecting ϕb_cmd according to ϕb_err, and ϕb_act to approach zero, and−K2*(ϕb_dot_cmd−ϕb_dot_act) is a feedback manipulated variable componenthaving the function of causing the deviation (ϕb_dot_cmd−ϕb_dot_act) toapproach zero.

Further, of −K1*((ϕb_cmd+Kdstb*ϕb_err)−ϕb_act), −K1*Kdstb*ϕb_err is amanipulated variable component having the function of applying a momentin the direction of further increasing the magnitude of ϕb_err (a momentin the roll direction) to the vehicle body 2.

In the present embodiment, in the case where the magnitude (absolutevalue) of ϕb_err is smaller than a predetermined value (in the casewhere ϕb_err takes a value in the dead band near zero), the posturecontrol arithmetic section 120 performs the computation of the aboveexpression (27) by setting Kdstb*ϕb_err=0, as in the case of the thirdembodiment. Therefore, the moment in the direction of further increasingthe magnitude of ϕb_err is applied to the vehicle body 2 on thecondition that the magnitude of ϕb_err is the predetermined value orgreater.

In the above-described manner, in the present embodiment, the posturecontrol arithmetic section 120 performs the arithmetic processing of theexpression (27), at each control processing cycle, to thereby calculatethe desired posture manipulation moment Msum_cmd.

Next, the first steering angle command determining section 103 receivesa desired posture manipulation moment Msum_cmd calculated in the posturecontrol arithmetic section 120.

The first steering angle command determining section 103 in the presentembodiment is the same as that in the second embodiment. Therefore, thefirst steering angle command determining section 103 determines adesired first steering angular acceleration δf1_dot2_cmd, a desiredfirst steering angular velocity δf1_dot_cmd, and a desired firststeering angle δf1_cmd through the arithmetic processing (of the aboveexpressions (24a) to (24c)) shown by the block and line diagram in FIG.22.

The present embodiment is identical to the third embodiment except forthe matters described above.

Here, the correspondence between the present embodiment and the presentinvention will be described supplementally. The posture controlarithmetic section 120 corresponds to the control input determiningsection in the present invention, and Msum_cmd calculated by the posturecontrol arithmetic section 120 corresponds to the control input in thepresent invention. The gain Kdstb in the above expression (27) performedby the posture control arithmetic section 120 corresponds to thesensitivity of the change in control input (Msum_cmd) to the change incenter-of-gravity displacement degree index value (estimated vehiclebody inclination angle displacement ϕb_err).

Otherwise, the correspondence between the present embodiment and thepresent invention is identical to that in the third embodiment.

According to the fourth embodiment described above, it is possible toachieve the effects similar to those in the third embodiment.

Fifth Embodiment

A fifth embodiment of the present invention will now be described.Referring to FIGS. 28A to 28C, a mobile body 201 of the presentembodiment is a straddle-ridden three-wheeled vehicle which includes avehicle body 202, and front wheels 203 f, 203 f and a rear wheel 203 rarranged spaced apart in the longitudinal direction of the vehicle body202. Hereinafter, the mobile body 201 will be referred to as“three-wheeled vehicle 201”.

FIGS. 28A to 28C show the three-wheeled vehicle 201 in a basic posturestate. The basic posture state of the three-wheeled vehicle 201 is theposture state when the three-wheeled vehicle 201 is traveling straightahead.

The three-wheeled vehicle 201 has two front wheels 203 f. 203 f arrangedspaced apart in the lateral direction (vehicle width direction) of thevehicle body 202.

In the following description, a symbol R will be added to the referencecharacters of any member on the right side (toward the front) of thevehicle body 202, and a symbol L will be added to the referencecharacters of any member on the left side of the vehicle body 202. Forexample, the front wheel 203 f on the right side will be denoted as thefront wheel 203 fR, and the front wheel 203 f on the left side will bedenoted as the front wheel 203 fL. The symbol R or L will be omittedwhen there is no need to differentiate between the right and left side.

The vehicle body 202 is provided with a boarding section 204 for anoperator (rider). In the present embodiment, the boarding section 204 isa seat for the operator (rider) to sit astride.

At the front portion of the vehicle body 202, front-wheel supportmechanisms 205L, 205R are arranged on the left side and the right side,respectively. A front wheel 203 f is pivotally supported at the lowerend portion of a front-wheel support mechanism 205. Each front wheel 203f is pivotally supported by the front-wheel support mechanism 205 on thesame side, via bearings or the like, such that the front wheel 203 f canrotate about its axle centerline.

The front-wheel support mechanisms 205L, 205R are coupled to the vehiclebody 202 via a mechanism which enables leaning of the vehicle body 202with respect to a contact ground surface S with which the front wheels203 f, 203 f and the rear wheel 203 r come into contact.

Specifically, pipes 206L, 206R are arranged on top of the respectivefront-wheel support mechanisms 205L, 205R. The front-wheel supportmechanisms 205L, 205R are attached to the corresponding pipes 206L, 206Rso as to be rotatable about steering axes CfL, CfR as the center axes ofthe respective pipes 206L, 206R. The steering axes CfL and CfR of thepipes 206L and 206R are tilted backward, parallel to each other.

The left and right pipes 206L and 206R are coupled via a parallel link207 which is made up of an upper link 207 u and a lower link 207 dspaced apart in the up-and-down direction and extending in the lateraldirection. Such a parallel link 207 is disposed on the front side andthe rear side of the pipes 206L, 206R.

The upper link 207 u and the lower link 207 d of a parallel link 207have their center portions pivotally supported so as to be swingableabout the axes in the longitudinal direction with respect to a supportstrut 208 which is secured to the front end of the vehicle body 202.

At the upper end of the support strut 208, an actuator 209 is mounted,which generates a rotative driving force to cause the parallel link 207to swing with respect to the vehicle body 202. The actuator 209 is madeup, for example, of an electric motor with a speed reducer. The outputshaft of the actuator 209 is coupled, via a link mechanism 210, to oneof the upper link 207 u and the lower link 207 d (for example, to theupper link 207 u) of the parallel link 207 of the pipes 206L, 206R.

In this case, the rotative driving force of the actuator 209 istransmitted to the parallel link 207 via the link mechanism 210. Suchtransmission of power makes it possible for the parallel link 207 toswing about the longitudinal axes with respect to the support strut 208(and hence, with respect to the vehicle body 202), as shown in FIG. 29A.As the parallel link 207 swings with respect to the vehicle body 202,the vehicle body 202 is rotatively driven in the roll direction withrespect to the front wheels 203 fL, 203 fR. As a result, as shown inFIG. 29A, the vehicle body 202 leans, together with the front wheels 203fL, 203 fR, with respect to the contact ground surface S.

It should be noted that the actuator 209 (hereinafter, referred to as“vehicle-body leaning actuator 209”) may be a hydraulic actuator, forexample, instead of the electric motor.

On the upper side of the support strut 208, a handlebar 220 is disposed.The handlebar 220 extends generally in the vehicle width direction.Although not shown in detail in the figure, the handlebar 220 isequipped with an accelerator grip, brake lever, turn signal switch, andso on.

This handlebar 220 is coupled to the front-wheel support mechanisms205L. 205R via a steering mechanism.

More specifically, a handlebar shaft 221 having a center axis(rotational axis) in the up-and-down direction is supported by thesupport strut 208 in a freely rotatable manner. The handlebar shaft 221penetrates through the support strut 208 in the up-and-down direction.The handlebar 220 is secured to the upper end of the handlebar shaft221. The handlebar axis is in parallel with the steering axis Cf of eachfront wheel 203 f.

A steering arm 222 is disposed to extend toward the front from the lowerend of the handlebar shaft 221 protruding downward from the supportstrut 208. Tie rods 223L and 223R are disposed to extend to the left andright, respectively, from the front end of the steering arm 222.

The left tie rod 223L has its respective ends coupled via sphericaljoints to the steering arm 222 and to the left front-wheel supportmechanism 205L. The right tie rod 223R has its respective ends coupledvia spherical joints to the steering arm 222 and to the rightfront-wheel support mechanism 205R.

In the above-described manner, the handlebar 220 is coupled to thefront-wheel support mechanisms 205L, 205R via the steering mechanismhaving the handlebar shaft 221, the steering arm 222, and the tie rods223L. 223R.

Therefore, as the handlebar 220 is rotated about the center axis of thehandlebar shaft 221, the front wheels 203 fR, 203 fL are steered inconjunction therewith, as shown in FIG. 29B.

At the rear portion of the vehicle body 202, a rear-wheel supportmechanism 225 for pivotally supporting the rear wheel 203 r is mounted.The rear wheel 203 r is pivotally supported by the rear-wheel supportmechanism 225, via bearings or the like, such that the rear wheel 203 rcan rotate about its axle centerline.

The rear-wheel support mechanism 225 is configured, for example, with asuspension mechanism including a swing arm, coil spring, damper, and soon.

Further, a rear-wheel driving actuator 230 as a power engine fortraveling of the three-wheeled vehicle 201 is mounted to the vehiclebody 202. The rear-wheel driving actuator 230 is made up of an electricmotor, for example. The rear-wheel driving actuator 230 transmits arotative driving force to the rear wheel 203 r via a power transmissionmechanism (not shown). As the power transmission mechanism, a mechanismincluding a chain, for example, may be adopted.

It should be noted that the rear-wheel driving actuator 230 may be ahydraulic actuator, for example, instead of the electric motor, or itmay be made up of an internal combustion engine.

The three-wheeled vehicle 201 of the present embodiment further includesthe configuration shown in FIG. 30 as the configuration for operationcontrol.

Specifically, as shown in FIG. 30, the three-wheeled vehicle 201includes a control device 260 which carries out control processing forcontrolling the operations of the aforesaid vehicle-body leaningactuator 209 and rear-wheel driving actuator 230.

The three-wheeled vehicle 201 further includes, as sensors for detectingvarious kinds of state quantities necessary for the control processingin the control device 260, a vehicle-body inclination detector 261 fordetecting an inclination angle in the roll direction of the vehicle body202, a steering angle detector 262 for detecting a steering angle of afront wheel 203 f, a handlebar torque detector 264 for detecting ahandlebar torque which is a steering force of the front wheels 203 fapplied via the handlebar 220 by an operator, a front-wheel rotationalspeed detector 265 for detecting a rotational speed (angular velocity)of a front wheel 203 f, and an accelerator manipulation detector 266 fordetecting an accelerator manipulated variable which is the manipulatedvariable (rotational amount) of the accelerator grip of the handlebar220. It should be noted that illustration of these detectors 261 to 266is omitted in FIGS. 28A to 28C, 29A, and 29B.

The control device 260 is an electronic circuit unit made up of a CPU,RAM. ROM, interface circuit, and so on. The control device 260 ismounted on an appropriate portion of the vehicle body 202. The controldevice 260 receives outputs (detection signals) from the respectivedetectors 261 to 266 described above.

The control device 260 may be made up of a plurality of mutuallycommunicable electronic circuit units. In this case, the electroniccircuit units constituting the control device 260 may be disposed inplaces distant from one another.

The vehicle-body inclination detector 261 is made up of an accelerationsensor and a gyro sensor (angular velocity sensor), for example. Thevehicle-body inclination detector 261 is mounted on an appropriateportion of the vehicle body 202. In this case, the control device 260carries out predetermined measurement and computation processing, suchas computation by a strapdown system, on the basis of the outputs fromthe acceleration sensor and the gyro sensor, to thereby measure theinclination angle in the roll direction (more specifically, inclinationangle in the roll direction with respect to the vertical direction(direction of gravitational force)) of the vehicle body 202.

In the description of the present embodiment, the inclination angle inthe roll direction of the vehicle body 202 in the basic posture state ofthe three-wheeled vehicle 201 is zero. The positive direction of theinclination angle in the roll direction corresponds to the directionthat makes the vehicle body 202 lean to the right (in the clockwisedirection) as the three-wheeled vehicle 201 is seen from behind.

The steering angle detector 262 is made up, for example, of a rotaryencoder or a potentiometer. In this case, the steering angle detector262 is attached to the aforesaid pipe 206R or 206L or the handlebarshaft 221, for example, so as to output a signal corresponding to therotation of either one of the front wheels 203 fR, 203 fL about thecorresponding steering axis CfR or CfL.

In the description of the present embodiment, the steering angle of afront wheel 203 f is zero in the basic posture state of thethree-wheeled vehicle 201. The positive direction of the steering anglecorresponds to the direction that makes each front wheel 203 f rotatecounterclockwise about the steering axis Cf as the three-wheeled vehicle201 is seen from above.

The handlebar torque detector 264 is made up, for example, of a forcesensor or a torque sensor disposed in a power transmission systembetween the handlebar 220 and the handlebar shaft 221, so as to output asignal corresponding to the handlebar torque that is applied from thehandlebar 220 side to the handlebar shaft 221.

In the description of the present embodiment, the positive direction ofthe handlebar torque corresponds to the direction of steering the frontwheels 203 f in the positive direction.

The front-wheel rotational speed detector 265 is made up, for example,of a rotary encoder attached to the axle of either one of the frontwheels 203 f, so as to output a signal corresponding to the rotationalspeed of that front wheel 203 f.

The accelerator manipulation detector 266 is made up, for example, of arotary encoder or a potentiometer built in the handlebar 220, so as tooutput a signal corresponding to the manipulated variable (rotationalamount) of the accelerator grip.

The functions of the above-described control device 260 will bedescribed further below. In the following description, an XYZ coordinatesystem, shown in FIGS. 28A and 28B, is used. This XYZ coordinate systemis a coordinate system in which, in the basic posture state of thethree-wheeled vehicle 201, the vertical direction (up-and-downdirection) is defined as the Z-axis direction, the longitudinaldirection of the vehicle body 202 as the X-axis direction, the lateraldirection of the vehicle body 202 as the Y-axis direction, and a pointon the contact ground surface S immediately beneath the overall centerof gravity G of the three-wheeled vehicle 201 as the origin. Thepositive directions of the X, Y, and Z axes are frontward, leftward, andupward, respectively.

In the present embodiment, for controlling the posture (inclinationangle) in the roll direction of the three-wheeled vehicle 201, atwo-mass-point model is used which describes the dynamic behavior of thethree-wheeled vehicle 201 (behavior related to the inclination in theroll direction of the vehicle body 202) using two mass points, as in theaforesaid first or second embodiment.

Therefore, in the present embodiment, the control device 260 controlsthe posture (inclination angle) in the roll direction of the vehiclebody 202 by controlling the inverted pendulum mass point lateralmovement amount Pb_diff_y, which is the amount of movement in the Y-axisdirection of the inverted pendulum mass point 71, as the controlledstate quantity.

In the present embodiment, however, the control of the posture(inclination angle) in the roll direction of the vehicle body 202 isperformed by the aforesaid vehicle-body leaning actuator 209 whichcauses the parallel link 207 to swing with respect to the vehicle body202.

In this control, the vehicle-body leaning actuator 209 is controlled soas to apply a moment component (a moment component in the rolldirection) in a direction to increase the lateral displacement of thecenter of gravity of the operator (a lateral displacement from the planeof symmetry of the vehicle body 202) to the vehicle body 202 in thelean-in or lean-out state, similarly as in the first or secondembodiment.

Further, in the present embodiment, the posture (inclination angle) inthe roll direction of the vehicle body 202 is controlled such that theinclination angle (roll angle) of the vehicle body 202 approaches aninclination angle according to the steering force of the front wheels203 f by the operator.

The functions of the control device 260 for carrying out such controlprocessing will now be described specifically. The suffixes “_act” and“_cmd” added to the reference characters in the following descriptionhave the same meanings as in the first through fourth embodiments.

The control device 260 includes, as functions implemented when the CPUexecutes installed programs (functions implemented by software) or asfunctions implemented by hardware configurations, the functions shown bythe block diagram in FIG. 31.

That is, the control device 260 includes: an estimated inverted pendulummass point lateral movement amount calculating section 281 whichcalculates an estimated inverted pendulum mass point lateral movementamount Pb_diff_y_act, an estimated inverted pendulum mass point lateralvelocity calculating section 282 which calculates an estimated invertedpendulum mass point lateral velocity Pb_diff_dot_y_act, a rider'scenter-of-gravity lateral displacement index value calculating section283 which calculates an estimated inverted pendulum mass point lateraldisplacement Pb_err1 as a rider's center-of-gravity lateral displacementindex value, and a desired posture state determining section 284 whichdetermines a desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd and a desired inverted pendulum mass point lateralvelocity Pb_diff_dot_y_cmd.

Here, the estimated inverted pendulum mass point lateral movement amountPb_diff_y_act, the estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_act, the estimated inverted pendulum mass pointlateral displacement Pb_err1, the desired inverted pendulum mass pointlateral movement amount Pb_diff_y_cmd, and the desired inverted pendulummass point lateral velocity Pb_diff_dot_y_cmd have the same technicalmeanings as in the aforesaid first or second embodiment.

The control device 260 further includes a rider-steering-based rollmanipulated variable calculating section 288 which calculates arider-steering-based roll manipulated variable Pb_err2 which is amanipulated variable for causing the roll angle ϕb of the vehicle body202 to approach an inclination angle appropriate to the steering forceof the front wheels 203 f caused by the operator's manipulation of thehandlebar 220.

In the present embodiment, the rider-steering-based roll manipulatedvariable is a correction amount for correcting the desired invertedpendulum mass point lateral movement amount Pb_diff_y_cmd.

The control device 260 further includes a posture control arithmeticsection 285 which determines a desired posture manipulation momentMsum_cmd as a manipulated variable (control input) for controlling theposture (inclination angle) in the roll direction of the vehicle body202 of the three-wheeled vehicle 201, and a desired traveling speeddetermining section 287 which determines a desired traveling speedVox_cmd of the three-wheeled vehicle 201.

Here, the desired posture manipulation moment Msum_cmd and the desiredtraveling speed Vox_cmd have the same technical meanings as in the firstor second embodiment.

The control device 260 carries out the processing in the above-describedfunctional sections successively at predetermined control processingcycles. The control device 260 controls the vehicle-body leaningactuator 209 in accordance with the desired posture manipulation momentMsum_cmd determined by the posture control arithmetic section 285.

Further, the control device 260 controls the rear-wheel driving actuator230 in accordance with the desired traveling speed Vox_cmd determined bythe desired traveling speed determining section 287.

Details of the control processing in the control device 260 will bedescribed below. In the arithmetic processing described below inrelation to the control processing in the control device 260, values ofthe parameters m, m1, m2, and h′ regarding the two-mass-point modeldescribed above and values of the parameters θcs, Lf, Lr, and Rgregarding the specification of the three-wheeled vehicle 201 are used.These parameters m, m1, m2, h′, θcs, Lf, Lr, and Rg have the sametechnical meanings as in the first embodiment. The values of theseparameters m, m1, m2, h′, θcs, Lf, Lr, and Rg are set values determinedin advance. Further, “g” in the arithmetic processing represents thegravitational acceleration constant.

The control device 260 carries out the processing in the estimatedinverted pendulum mass point lateral movement amount calculating section281 at each control processing cycle.

As shown in FIG. 32, the estimated inverted pendulum mass point lateralmovement amount calculating section 281 receives: a detected roll angleϕb_act which is a detected value of the inclination angle in the rolldirection (roll angle) of the vehicle body 202, and a detected steeringangle δf_act which is a detected value of the steering angle δf of afront wheel 203 f.

The detected roll angle ϕb_act is a detected value (observed value)indicated by an output from the vehicle-body inclination detector 261,and the detected steering angle δf_act is a detected value (observedvalue) indicated by an output from the steering angle detector 262.

The estimated inverted pendulum mass point lateral movement amountcalculating section 281 calculates an estimated inverted pendulum masspoint lateral movement amount Pb_diff_y_act by the arithmetic processingshown by the block and line diagram in FIG. 32. That is, the estimatedinverted pendulum mass point lateral movement amount calculating section281 calculates Pb_diff_y_act by the arithmetic processing of thefollowing expressions (30a) to (30c).Pb_diff_y_=−h′*ϕb_act  (30a)Pb_diff_y_2=Plfy(δf_act)*(Lr/L)  (30b)Pb_diff_y_act=Pb_diff_y_1+Pb_diff_y_2  (30c)

In FIG. 32, processing sections 281-1, 281-2, and 281-3 representprocessing sections which perform the arithmetic processing of theexpressions (30a), (30b), and (30c), respectively.

Here, Plfy(δf_act) in the expression (30b) is a function value which isdetermined in a processing section 281-2-1 in FIG. 32, from the value ofδf_act, by a preset conversion function Plfy(δf). This conversionfunction Plfy(δf) is configured, for example, by a mapping or anarithmetic expression. In the present embodiment, the conversionfunction Plfy(δf) has been set, as illustrated by the graph in theprocessing section 281-2-1, such that the value of Plfy increases from avalue on the negative side to a value on the positive side as the valueof the steering angle δf of a front wheel 203 f increases (from a valueon the negative side to a value on the positive side).

In the above-described manner, the estimated inverted pendulum masspoint lateral movement amount calculating section 281 performs thearithmetic processing of the above expressions (30a) to (30c), at eachcontrol processing cycle, to thereby calculate the estimated invertedpendulum mass point lateral movement amount Pb_diff_y_act.

Supplementally, the conversion function in the processing section281-2-1 may be set such that a value of Plfy(δf_act)*(Lr/L) is obtainedin the processing section 281-2-1. In this case, the output from theprocessing section 281-2-1, as it is, is calculated as Pb_diff_y_2.

Next, the control device 260 carries out the processing in the estimatedinverted pendulum mass point lateral velocity calculating section 282.

The estimated inverted pendulum mass point lateral velocity calculatingsection 282 differentiates (obtains the temporal change rate of) theestimated inverted pendulum mass point lateral movement amountPb_diff_y_act calculated in the estimated inverted pendulum mass pointlateral movement amount calculating section 281, to calculate anestimated inverted pendulum mass point lateral velocityPb_diff_dot_y_act, as shown by the following expression (31).Pb_diff_dot_y_act=differential (temporal change rate) ofPb_diff_y_act  (31)

The control device 260 further carries out the processing in the rider'scenter-of-gravity lateral displacement index value calculating section283. The rider's center-of-gravity lateral displacement index valuecalculating section 283 receives, as shown in FIG. 33, an estimatedinverted pendulum mass point lateral movement amount Pb_diff_y_actcalculated in the estimated inverted pendulum mass point lateralmovement amount calculating section 281, a detected steering angleδf_act of a front wheel 203 f, an estimated front-wheel rotationaltransfer velocity Vf_act, and a value (last time's value) Msum_cmd_p ofthe desired posture manipulation moment Msum_cmd calculated by theposture control arithmetic section 285 in the last time's controlprocessing cycle.

The estimated front-wheel rotational transfer velocity Vf_act is avelocity which is calculated by multiplying the detected value (observedvalue) of the rotational angular velocity of a front wheel 203 f,indicated by an output from the aforesaid front-wheel rotational speeddetector 265, by the predetermined effective rolling radius of the frontwheel 203 f.

Further, Msum_cmd_p corresponds to a pseudo estimate (observed value) ofthe moment (posture manipulation moment) in the roll direction acting onthe vehicle body 202 by the driving force of the vehicle-body leaningactuator 209.

The rider's center-of-gravity lateral displacement index valuecalculating section 283 calculates an estimated inverted pendulum masspoint lateral displacement Pb_err1 as a rider's center-of-gravitylateral displacement index value, through the arithmetic processingshown by the block and line diagram in FIG. 33. In this case, therider's center-of-gravity lateral displacement index value calculatingsection 283 is configured as an observer.

Specifically, the rider's center-of-gravity lateral displacement indexvalue calculating section 283 calculates an estimate of the roll momentinertial force component Mi, an estimate of the roll moment floorreaction force component Mp, and an estimate of the roll moment groundsurface mass point component M2 by a roll moment inertial forcecomponent calculating section 283-2, a roll moment floor reaction forcecomponent calculating section 283-3, and a roll moment ground surfacemass point component calculating section 283-4, respectively, on thebasis of the input values of δf_act and Vf_act.

Here, the roll moment inertial force component Mi, the roll moment floorreaction force component Mp, and the roll moment ground surface masspoint component M2 have the same technical meanings as in the aforesaidfirst or second embodiment.

The specific processing in the calculating sections 283-2, 283-3, and283-4 will be described later.

Then, the rider's center-of-gravity lateral displacement index valuecalculating section 283 carries out, in a processing section 283-5,arithmetic processing based on a dynamic model taking account of lateraldisplacement of the inverted pendulum mass point 71 due to lateraldisplacement of the center of gravity of the operator, on the basis ofthe estimates of Mi, Mp, and M2, the input value of Pb_diff_y_act, thelast time's value Msum_cmd_p of Msum_cmd, and a value (last time'svalue) Pb_err1_p of the estimated inverted pendulum mass point lateraldisplacement Pb_err1 calculated in the last time's control processingcycle, to thereby calculate an estimate of a translational accelerationPb_diff_dot2_y in the Y-axis direction of the inverted pendulum masspoint 71.

Stated differently, the last time's value Pb_err1_p corresponds to thelatest one of the estimated inverted pendulum mass point lateraldisplacements Pb_err1 calculated up to then.

Here, in the present embodiment, the dynamic model (equation of motionof the inverted pendulum mass point 71) taking account of the lateraldisplacement of the inverted pendulum mass point 71 due to the lateraldisplacement of the center of gravity of the operator is expressed by anequation of motion that is obtained by replacing Pb_diff_y, on the rightside of the above expression (2) with Pb_diff_y_act+Pb_err1 and alsoreplacing −Mp−M2−Mi with −Mp−M2−Mi−Msum (where Msum is a posturemanipulation moment of the vehicle body 202 by the vehicle-body leaningactuator 209).

Therefore, the arithmetic processing in the processing section 283-5 iscarried out in accordance with the following expression (32a).Pb_diff_dot2y=(m1*g*(Pb_diff_act+Pb_err1_p)−Mp−M2−Mi−Msum_cmd_p)/(m1*h′)  (32a)

Then, the rider's center-of-gravity lateral displacement index valuecalculating section 283 integrates, in a processing section 283-6,Pb_diff_dot2′ calculated by the above expression (32a), to therebycalculate a first estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_1 as a first estimate of the moving velocity (asseen in the XYZ coordinate system) in the Y-axis direction of theinverted pendulum mass point 71, as shown by the following expression(32b).Pb_diff_dot_y_1=integral of Pb_diff_dot2_y  (32b)

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 283 performs, in a processing section 283-1, adifferential operation on the input value of Pb_diff_y_act, to therebycalculate a second estimated inverted pendulum mass point lateralvelocity Pb_diff_dot_y_2 as a second estimate of the moving velocity (asseen in the XYZ coordinate system) in the Y-axis direction of theinverted pendulum mass point 71, as shown by the following expression(32c).Pb_diff_dot_y_2=differential (temporal change rate) ofPb_diff_y_act  (32c)

It should be noted that Pb_diff_dot_y_2 calculated by the expression(32c) is the same as Pb_diff_dot_y_act calculated by the aboveexpression (31) by the estimated inverted pendulum mass point lateralvelocity calculating section 282. Therefore, Pb_diff_dot_y_actcalculated in the estimated inverted pendulum mass point lateralvelocity calculating section 282 may be used, without modification, asthe second estimated inverted pendulum mass point lateral velocityPb_diff_dot_y_2.

Here, the second estimated inverted pendulum mass point lateral velocityPb_diff_dot_y_2 calculated by the expression (32c) corresponds to anestimate of the moving velocity in the Y-axis direction of the invertedpendulum mass point 71 on the assumption that there is no lateraldisplacement of the center of gravity of the operator.

Therefore, the deviation between this second estimated inverted pendulummass point lateral velocity Pb_diff_dot_y_2 and the first estimatedinverted pendulum mass point lateral velocity Pb_diff_dot_y_1,calculated dynamically according to the above expressions (32a) and(32b), becomes a value depending on the inverted pendulum mass pointlateral displacement amount Pb_err1 caused by the lateral displacementof the center of gravity of the operator.

Therefore, the rider's center-of-gravity lateral displacement indexvalue calculating section 283 calculates the estimated inverted pendulummass point lateral displacement Pb_err1 in a processing section 283-7 bythe arithmetic processing of the following expression (32d).

$\begin{matrix}\begin{matrix}{{Pb\_ err1} = {\left( {{{Pb\_ diff}{\_ dot}{\_ y}\_ 2} - {{Pb\_ diff}{\_ dot}{\_ y}\_ 1}} \right)*}} \\{{Kestm}*{\left( {m\; 1*h^{\prime}} \right)/\left( {m\; 1*g} \right)}} \\{= {\left( {{{Pb\_ diff}{\_ dot}{\_ y}\_ 2} - {{Pb\_ diff}{\_ dot}{\_ y}\_ 1}} \right)*}} \\{{Kestm}*{h^{\prime}/g}}\end{matrix} & \left( {32d} \right)\end{matrix}$

Kestm used in the arithmetic processing of this expression (32d) is apredetermined gain of a predetermined value. It should be noted thatKestm*h′/g in the expression (32d) may be set in advance as a singlegain value.

Supplementally, in the block and line diagram in FIG. 33, a last time'svalue (=Pb_err1_p*m1*g) of(Pb_diff_dot_y_2−Pb_diff_dot_y_1)*Kestm*(m1*h′) is input to theprocessing section 283-5 from the processing section 283-7.Alternatively, a last time's value Pb_err1_p of the estimated invertedpendulum mass point lateral displacement Pb_err1, for example, may beinput directly to the processing section 283-5.

In the above-described manner, the rider's center-of-gravity lateraldisplacement index value calculating section 283 calculates theestimates of Mi, Mp, and M2, and uses these estimates, the estimatedinverted pendulum mass point lateral movement amount Pb_diff_act, andthe last time's value Msum_cmd_p of Msum_cmd to perform the arithmeticprocessing of the expressions (32a) to (32d), to thereby calculate theestimated inverted pendulum mass point lateral displacement Pb_err1.

In this case, the estimates of Mi, Mp, and M2 are calculated in themanner as described below.

First, the roll moment inertial force component calculating section283-2 in the rider's center-of-gravity lateral displacement index valuecalculating section 283 calculates an estimate of the roll momentinertial force component Mi by the arithmetic processing shown by theblock and line diagram in FIG. 34. That is, the roll moment inertialforce component calculating section 283-2 calculates the estimate of theroll moment inertial force component Mi by the arithmetic processing ofthe following expressions (33a) to (33f).δ′f_act=δf_act*cos(θcs)  (33a)Voy_act=sin(δf_act)*Vf_act*(Lr/L)  (33b)Voy_dot_act=differential (temporal change rate) of Voy_act  (33c)ωz_act=sin(δ′f_act)*Vf_act*(1/L)  (33d)Vox_act=cos(δ′f_act)*Vf_act  (33e)Mi=(Voy_dot_act+ωz_act*Vox_act)*m1*h′  (33f)

It should be noted that δ′f_act, Voy_act, Voy_dot_act, ωz_act, andVox_act calculated by the above expressions (33a) to (33e),respectively, have the same technical meanings as those calculated bythe arithmetic processing (expressions (13a) to (13e)) of the rollmoment inertial force component calculating section 83-2 in the first orsecond embodiment.

In FIG. 34, a processing section 283-2-1 represents a processing sectionwhich performs the arithmetic processing of the expressions (33a) and(33b), a processing section 283-2-2 represents a processing sectionwhich performs the arithmetic processing (differential operation) of theexpression (33c), a processing section 283-2-3 represents a processingsection which performs the arithmetic processing of the expressions(33a) and (33d), a processing section 283-2-4 represents a processingsection which performs the arithmetic processing of the expressions(33a) and (33e), and a processing section 283-2-5 represents aprocessing section which performs the arithmetic processing of theexpression (33f).

In the above-described manner, the roll moment inertial force componentcalculating section 283-2 performs the arithmetic processing of theabove expressions (33a) to (33f), to thereby calculate the estimate ofthe roll moment inertial force component Mi.

Supplementally, for example in the case where an angular velocity sensorfor detecting an angular velocity in the yaw direction is mounted on thevehicle body 202 of the three-wheeled vehicle 201, a detected value ofthe angular velocity in the yaw direction indicated by an output fromthat angular velocity sensor may be used as a value of ωz_act in theexpression (33f). In this case, the arithmetic processing (expression(33d)) in the processing section 283-2-3 is unnecessary.

Furthermore, for example in the case where a rear-wheel rotational speeddetector for detecting a rotational speed (angular velocity) of the rearwheel 203 r of the three-wheeled vehicle 201 is mounted on thethree-wheeled vehicle 201, an estimate of the translational movingvelocity of the rear wheel 203 r obtained by multiplying the detectedvalue of the rotational speed of the rear wheel 203 r indicated by anoutput from that rear-wheel rotational speed detector by the effectiverolling radius of the rear wheel 203 r may be used as a value of Vox_actin the expression (33f). In this case, the arithmetic processing(expression (33e)) in the processing section 283-2-4 is unnecessary.

Next, the roll moment floor reaction force component calculating section283-3 in the rider's center-of-gravity lateral displacement index valuecalculating section 283 calculates an estimate of the roll moment floorreaction force component Mp by the arithmetic processing shown by theblock and line diagram in FIG. 35. That is, the roll moment floorreaction force component calculating section 283-3 calculates theestimate of the roll moment floor reaction force component Mp by thearithmetic processing of the following expressions (34a) to (34c).p1=Pfy(δf_act)*(Lr/L)  (34a)p2=Plfy(f_act)*(Lr/L)*(−Rg/h′)  (34b)Mp=(p1+p2)*m*g  (34c)It should be noted that p1 and p2 calculated by the above expressions(34a) and (34b), respectively, have the same technical meanings as thosecalculated by the arithmetic processing (expressions (14a) and (14b)) ofthe roll moment floor reaction force component calculating section 83-3in the first or second embodiment.

In FIG. 35, a processing section 283-3-1 represents a processing sectionwhich performs the arithmetic processing of the expression (34a), aprocessing section 283-3-2 represents a processing section whichperforms the arithmetic processing of the expression (34b), and aprocessing section 283-3-3 represents a processing section whichperforms the arithmetic processing of the expression (34c).

Here, Pfy(δf_act) in the expression (34a) is a function value which isdetermined by a preset conversion function Pfy(f) from the value ofδf_act in a processing section 283-3-1-1 in the processing section283-3-1 in FIG. 35. This conversion function Pfy(δf) is configured, forexample, by a mapping or an arithmetic expression. The conversionfunction Pfy(δf) has been set, as illustrated by the graph in theprocessing section 283-3-1-1, such that the value of Pfy increasesmonotonically from a value on the negative side to a value on thepositive side as the value of δf increases (from a value on the negativeside to a value on the positive side).

Further, the arithmetic processing of the computation of the right sideof the expression (34b) excluding the multiplication of (−Rg/h′), i.e.the arithmetic processing in a processing section 283-3-2-1 in theprocessing section 283-3-2, is the same as the processing (ofcalculating Pb_diff_y_2) of the processing section 281-2 in thearithmetic processing of the aforesaid estimated inverted pendulum masspoint lateral movement amount calculating section 281.

Therefore, the expression (34b) is equivalent to the followingexpression (34b′).p2=Pb_diff_y_2*(−Rg/h′)  (34b′)In the above-described manner, the roll moment floor reaction forcecomponent calculating section 283-3 calculates an estimate of the rollmoment floor reaction force component Mp by the arithmetic processing ofthe above expressions (34a) to (34c).

Supplementally, in the processing section 283-3-1, a conversion functionfor obtaining a value (=p1) of (Pfy(δf_act)*(Lr/L)) as a function valuemay be used instead of the conversion function Pfy(δf). In this case, p1is obtained directly from the conversion function.

Further, the modifications explained supplementally about the processingsection 281-2 in the estimated inverted pendulum mass point lateralmovement amount calculating section 281 may also be adopted for theprocessing section 283-3-2-1 in the processing section 283-3-2.

Further, in the arithmetic processing in the processing section 283-3-2,a conversion function for obtaining a value of(Plfy(δf_act)*(Lr/L)*(−Rg/h′)) as a function value may be used insteadof the conversion function Plfy(δf). In this case, the output value ofthe conversion function, as it is, is obtained as p2.

Next, the roll moment ground surface mass point component calculatingsection 283-4 in the rider's center-of-gravity lateral displacementindex value calculating section 283 calculates an estimate of the rollmoment ground surface mass point component M2 by the arithmeticprocessing shown by the block and line diagram in FIG. 36. That is, theroll moment ground surface mass point component calculating section283-4 calculates the estimate of the roll moment ground surface masspoint component M2 by the arithmetic processing of the followingexpressions (35a) and (35b).q=Plfy(δf_act)*(Lr/L)  (35a)M2=q*(−m2*g)  (35b)

It should be noted that q calculated by the above expression (35a) hasthe same technical meaning as that calculated by the arithmeticprocessing (expression (15a)) of the roll moment ground surface masspoint component calculating section 83-4 in the first or secondembodiment.

In FIG. 36, a processing section 283-4-1 represents a processing sectionwhich performs the arithmetic processing of the expression (35a), and aprocessing section 283-4-2 represents a processing section whichperforms the arithmetic processing of the expression (35b).

In this case, the arithmetic processing in the processing section283-4-1 is the same as the arithmetic processing (of calculatingPb_diff_y_2) of the processing section 281-2 in the arithmeticprocessing of the aforesaid estimated inverted pendulum mass pointlateral movement amount calculating section 281. Therefore, in thearithmetic processing of the processing section 283-4-1, Pb_diff_y_2 iscalculated as the lateral movement amount q of the ground surface masspoint 72.

In the above-described manner, the roll moment ground surface mass pointcomponent calculating section 283-4 calculates an estimate of the rollmoment ground surface mass point component M2 by the arithmeticprocessing of the above expressions (35a) and (35b).

Supplementally, the modifications explained supplementally about theprocessing section 281-2 in the estimated inverted pendulum mass pointlateral movement amount calculating section 281 may also be adopted forthe processing section 283-4-1.

Further, instead of the conversion function Plfy(δf), a conversionfunction for obtaining a value of Plfy(δf_act)*(Lr/L)*(−m2*g) as afunction value may be used. In this case, the output value of theconversion function, as it is, is obtained as the roll moment groundsurface mass point component M2.

Returning to FIG. 31, the control device 260 further carries out theprocessing in the desired posture state determining section 284.

In the present embodiment, the desired posture state determining section284 determines a desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd, as in the desired posture state determiningsection 84 in the first or second embodiment.

That is, the desired posture state determining section 284 determines adesired inverted pendulum mass point lateral movement amountPb_diff_y_cmd by the arithmetic processing of the following expressions(36a) and (36b), using ωz_act (estimate of the angular velocity in theyaw direction) calculated by the arithmetic processing of the aboveexpression (33d), and Vox_act (estimate of the traveling speed)calculated by the arithmetic processing of the expression (33e). In thepresent embodiment, the desired posture state determining section 284sets a desired inverted pendulum mass point lateral velocityPb_diff_dot_y_cmd to zero.ϕb_lean=−Vox_act*ωz_act/g  (36a)Pb_diff_y_cmd=ϕb_lean*h′  (36b)It should be noted that the desired inverted pendulum mass point lateralvelocity Pb_diff_dot_y_cmd may be determined variably in accordancewith, for example, the detected steering angle δf_act.

Further, the desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd may be set to zero, for example. Alternatively, thedesired inverted pendulum mass point lateral movement amountPb_diff_y_cmd may be determined variably in accordance with, forexample, the detected steering angle δf_act.

The control device 260 further carries out the processing in therider-steering-based roll manipulated variable calculating section 288.The rider-steering-based roll manipulated variable calculating section288 receives a detected steering angle δf_act and a detected handlebartorque Th_act, as shown in FIG. 37.

The detected handlebar torque Th_act is a detected value indicated by anoutput from the aforesaid handlebar torque detector 264.

The rider-steering-based roll manipulated variable calculating section288 calculates a rider-steering-based roll manipulated variable Pb_err2as a correction amount of the desired inverted pendulum mass pointlateral movement amount Pb_diff_y_cmd by the arithmetic processing shownby the block and line diagram in FIG. 37.

Specifically, the rider-steering-based roll manipulated variablecalculating section 288 calculates the rider-steering-based rollmanipulated variable Pb_err2 by the arithmetic processing of thefollowing expressions (37a) and (37b).Tstr=Kstr*Th_act−Mself(δf_act)  (37a)Pb_err2=Kcmv*Tstr*(1(m1*g))  (37b)Here, Kstr*Th_act on the right side of the expression (37a) correspondsto an estimate of the steering torque of the front wheels 203 f(resultant torque of the torques about the steering axes CfR and CfL ofthe respective front wheels 203 fR and 203 fL) according to thehandlebar torque Th_act. In this case, Kstr is a coefficient of apredetermined value. The positive direction of the steering torque is acounterclockwise direction when the three-wheeled vehicle 201 is seenfrom above.

Further, Mself(δf_act) on the right side of the expression (37a) is amoment (hereinafter, referred to as “self-steering moment”) in thesteering direction of the front wheels 203 f which is generatedspontaneously (without manipulation of the handlebar 220) by thephenomenon called “self-steering” in the three-wheeled vehicle 201.

The self-steering moment Mself(δf_act) is a function value which isdetermined by a preset conversion function Mself(δf) from the value ofδf_act in a processing section 288-1 in FIG. 37. This conversionfunction Mself(δf) is configured, for example, by a mapping or anarithmetic expression. The conversion function Mself(δf) has been set,as illustrated by the graph in the processing section 288-1, such thatthe value of Mself increases monotonically from a value on the negativeside to a value on the positive side as the value of δf increases (froma value on the negative side to a value on the positive side).

Therefore, Tstr calculated by the expression (37a) is a component of thesteering torque of the front wheels 203 f according to the handlebartorque Th_act, excluding the self-steering moment Mself(δf_act). Thiscomponent corresponds to the steering torque (steering force) of thefront wheels 203 f that is intended by the operator through manipulationof the handlebar 220.

Further, Kcmv*Tstr on the right side of the expression (37b) is forconverting the steering torque Tstr, calculated by the expression (37a),into a moment in the roll direction of the vehicle body 202. In thiscase, Kcmv is a conversion factor of a predetermined value.

The rider-steering-based roll manipulated variable Pb_err2 is calculatedby dividing this moment Kcmv*Tstr by m1*g.

In this manner, the rider-steering-based roll manipulated variablePb_err2 for correcting the desired inverted pendulum mass point lateralmovement amount Pb_diff_y_cmd so as to make the vehicle body 202 leanaccording to the steering torque Tstr of the front wheels 203 f by theoperator's manipulation of the handlebar 220 is calculated.

In this case, in the case where the estimate Tstr of the steering torqueis a torque in the positive (or, counterclockwise) direction, therider-steering-based roll manipulated variable Pb_err2 is determined tobecome a manipulated variable in the direction making the vehicle body202 lean to the left. In the case where the estimate Tstr of thesteering torque is a torque in the negative (or, clockwise) direction,the rider-steering-based roll manipulated variable Pb_err2 is determinedto become a manipulated variable in the direction making the vehiclebody 202 lean to the right.

In the above-described manner, the rider-steering-based roll manipulatedvariable calculating section 288 calculates the rider-steering-basedroll manipulated variable Pb_err2 by the arithmetic processing of theexpressions (37a) and (37b).

Next, the control device 260 carries out the processing in the posturecontrol arithmetic section 285. As shown in FIG. 38, the posture controlarithmetic section 285 receives: a desired inverted pendulum mass pointlateral movement amount Pb_diff_y_cmd and a desired inverted pendulummass point lateral velocity Pb_diff_dot_y_cmd determined in the desiredposture state determining section 284, an estimated inverted pendulummass point lateral movement amount Pb_diff_y_act calculated in theestimated inverted pendulum mass point lateral movement amountcalculating section 281, an estimated inverted pendulum mass pointlateral velocity Pb_diff_dot_y_act calculated in the estimated invertedpendulum mass point lateral velocity calculating section 282, anestimated inverted pendulum mass point lateral displacement Pb_err1calculated in the rider's center-of-gravity lateral displacement indexvalue calculating section 283, and a rider-steering-based rollmanipulated variable Pb_err2 calculated in the rider-steering-based rollmanipulated variable calculating section 288.

The posture control arithmetic section 285 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 38, to determine a desired posture manipulation moment Msum_cmd.

That is, the posture control arithmetic section 285 calculates thedesired posture manipulation moment Msum_cmd by the arithmeticprocessing of the following expression (38).Msum_cmd=−K*((Pb_diff_y_cmd+Kdstb1*Pb_err1−Kdstb2*Pb_err2)−Pb_diff_y_act)−K2*(Pb_diff_dot_y_cmd−Pb_diff_dot_y_act)  (38)

Here, Kdstb1, Kdstb2, K1, and K2 in the expression (38) are gains ofpredetermined values. The values of these gains Kdstb1, Kdstb2, K1, andK2 are set variably in accordance with, for example, the estimatedtraveling speed Vox_act of the three-wheeled vehicle 201, or thedetected steering angle δf_act.

In this case, in the present embodiment, the values of the gains Kdstb1,Kdstb2, K1, and K2 are set such that the moment in the roll directionacting on the vehicle body 202 by the actuation of the vehicle-bodyleaning actuator 209 according to Msum_cmd will become not so large(such that the operator can lean the vehicle body 202 in the rolldirection relatively easily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb1, Kdstb2, K1, and K2 are allset such that the) vary in accordance with the estimated traveling speedVox_act of the three-wheeled vehicle 201.

For example, the magnitudes of the gains Kdstb2, K1, and K2 are all setvariably such that the become smaller as the estimated traveling speedVox_act of the three-wheeled vehicle 201 is higher.

Kdstb1*Pb_err1 in the expression (38) is a correction amount, applicablein the lean-out or lean-in state, for correcting the desired invertedpendulum mass point lateral movement amount Pb_diff_y_cmd, determined inthe desired posture state determining section 284, in such a way as toincrease the lateral displacement of the center of gravity of theoperator (thereby enhancing the lean-out or lean-in state).

Further, Kdstb2*Pb_err2 in the expression (38) is a correction amountfor correcting the desired inverted pendulum mass point lateral movementamount Pb_diff_y_cmd so as to make the vehicle body 202 lean accordingto the steering force of the front wheels 203 f by the operator.

Further, in the expression (38),−K1*((Pb_diff_y_cmd+Kdstb1*Pb_err1−Kdstb2*Pb_err2)−Pb_diff_y_act) is afeedback manipulated variable component having the function of causingthe deviation between the desired value(Pb_diff_y_cmd+Kdstb1*Pb_err1−Kdstb2*Pb_err2), obtained by correctingPb_diff_y_cmd according to Pb_err1 and Pb_err2, and Pb_diff_y_act toapproach zero, and −K2*(Pb_diff_dot_y_cmd−Pb_diff_dot_y_act) is afeedback manipulated variable component having the function of causingthe deviation (Pb_diff_dot_y_cmd−Pb_diff_dot_y_act) to approach zero.

Of −K1*((Pb_diff_y_cmd+Kdstb1*Pb_err1−Kdstb2*Pb_err2)−Pb_diff_y_act),−K1*Kdstb1*Pb_err1 is a manipulated variable component having thefunction of applying a moment in the direction of further increasing themagnitude of Pb_err1 (a moment in the roll direction) to the vehiclebody 202.

In the present embodiment, in the case where the magnitude (absolutevalue) of Pb_err1 is smaller than a predetermined value (in the casewhere Pb_err1 takes a value in the dead band near zero), the posturecontrol arithmetic section 285 performs the computation of the aboveexpression (38) by setting Kdstb1*Pb_err1=0, as in the case of the firstembodiment. Therefore, the moment in the direction of further increasingthe magnitude of Pb_err1 is applied to the vehicle body 202 on thecondition that the magnitude of Pb_err1 is the predetermined value orgreater.

In the above-described manner, in the present embodiment, the posturecontrol arithmetic section 285 performs the arithmetic processing of theexpression (38), at each control processing cycle, to thereby calculatethe desired posture manipulation moment Msum_cmd.

The control device 260 further carries out the processing in the desiredtraveling speed determining section 287. The processing in the desiredtraveling speed determining section 287 is the same as, for example, theprocessing in the desired traveling speed determining section 87 in thefirst through fourth embodiments.

Therefore, a desired traveling speed Vox_cmd is determined by theprocessing shown by the block and line diagram in FIG. 17, for example.

A description will now be made about the control of the aforesaidvehicle-body leaning actuator 209 and rear-wheel driving actuator 230.

The control device 260 controls the vehicle-body leaning actuator 209 inaccordance with the desired posture manipulation moment Msum_cmddetermined in the posture control arithmetic section 285. In this case,the control device 260 converts Msum_cmd into a desired output torque ofthe vehicle-body leaning actuator 209 by a predetermined arithmeticexpression or mapping which is set in advance. The control device 260then controls the electric current passed through the vehicle-bodyleaning actuator 209 (electric motor), in accordance with an electriccurrent command value that is determined according to the desired outputtorque.

Further, the control device 260 determines an electric current commandvalue for the rear-wheel driving actuator 230 (electric motor), from thedesired traveling speed Vox_cmd determined in the desired travelingspeed determining section 287 and the estimated traveling speed Vox_actcalculated by the above expression (33e), by the processing similar tothat in the front-wheel driving actuator control section 92 in the firstthrough fourth embodiments (see FIG. 19). The control device 260 thencontrols the electric current passed through the rear-wheel drivingactuator 230 in accordance with the determined electric current commandvalue.

The above has described the details of the control processing in thecontrol device 260 according to the present embodiment.

Here, the correspondence between the present embodiment and the presentinvention will be described.

In the present embodiment, the vehicle-body leaning actuator 209corresponds to the actuator in the present invention. In this case, thevehicle-body leaning actuator 209 primarily has the function as anactuator which causes the vehicle body 202 to swing in the rolldirection with respect to the road surface. The vehicle-body leaningactuator 209 also has the function as an actuator which moves the centerof gravity of the vehicle body 202 in the lateral direction (Y-axisdirection).

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 283 corresponds to the center-of-gravitydisplacement degree index value determining section in the presentinvention. In this case, the estimated inverted pendulum mass pointlateral displacement Pb_err1 corresponds to the center-of-gravitydisplacement degree index value in the present invention. Further, theposition on the plane of symmetry of the vehicle body 202 corresponds tothe predetermined reference position related to the position of thecenter of gravity of the operator.

Further, the estimated front-wheel rotational transfer velocity Vf_act,the detected steering angle δf_act, the last time's value Msum_cmd_p(which corresponds to a pseudo estimate of posture manipulation moment)of the desired posture manipulation moment Msum_cmd, and the secondestimated inverted pendulum mass point lateral velocity Pb_diff_dot_y_2as a differential value of the estimated inverted pendulum mass pointlateral movement amount Pb_diff_y_act correspond to the observed valuesof the motional state of the mobile body (three-wheeled vehicle 201)used in the processing of the center-of-gravity displacement degreeindex value determining section (rider's center-of-gravity lateraldisplacement index value calculating section 283). In this case,Pb_diff_dot_y_2 corresponds to the observed value of the inclinationstate quantity of the vehicle body 202.

Further, the above expressions (32a) and (32b) correspond to thedynamics computation in the present invention. The first estimatedinverted pendulum mass point lateral velocity Pb_diff_dot_y_1 calculatedby the expression (32b) corresponds to the calculated value of theinclination state quantity of the vehicle body 202.

Further, the rider-steering-based roll manipulated variable calculatingsection 288 includes the function as the steering force estimatingsection in the present invention. Specifically, the processing of theabove expression (37a) corresponds to the steering force estimatingsection.

The posture control arithmetic section 285 corresponds to the controlinput determining section in the present invention, and Msum_cmdcalculated by the posture control arithmetic section 285 corresponds tothe control input in the present invention.

The gain Kdstb1 in the above expression (38a) performed by the posturecontrol arithmetic section 285 corresponds to the sensitivity of thechange in control input (Msum_cmd) to the change in center-of-gravitydisplacement degree index value (estimated inverted pendulum mass pointlateral displacement Pb_err1).

According to the fifth embodiment described above, in the state wherethe center of gravity of the operator is located on the plane ofsymmetry of the vehicle body 202 (i.e. in the reference position) or inthe state close thereto (including the state where the absolute value ofPb_err1 is smaller than the predetermined value), divergence of theestimated inverted pendulum mass point lateral movement amountPb_diff_y_act from a desired inverted pendulum mass point lateralmovement amount Pb_diff_y_cmd is prevented.

In the case where the center of gravity of the operator has beendisplaced laterally from the reference position to a lean-in or lean-outstate (specifically, upon occurrence of lateral displacement causingPb_err1 to take an absolute value of the predetermined value orgreater), the vehicle-body leaning actuator 209 is controlled in such amanner that a momentin the direction of further increasing the lateraldisplacement (a moment in the roll direction) is applied to the vehiclebody 202. As a result, it becomes readily possible for an operator toquickly realize a lean-in or lean-out state when the operator shiftshis/her weight in an attempt to achieve the lean-in or lean-out state.It is therefore possible to improve the maneuverability of thethree-wheeled vehicle 201 at the time of turning.

In addition, the rotative driving force of the vehicle-body leaningactuator 209 is controlled so as to make the roll angle ϕb_act of thevehicle body 202 approach the inclination angle according to thesteering force of the front wheels 203 f generated by the operator'smanipulation of the handlebar 220.

It is therefore possible to make the vehicle body 202 lean in responseto a request of turning the three-wheeled vehicle 201 according to thesteering of the front wheels 203 f by the operator.

Sixth Embodiment

A sixth embodiment of the present invention will be described below withreference to FIGS. 39 to 42. The mobile body in the present embodimentis the same as the mobile body (three-wheeled vehicle 201) in the fifthembodiment. The present embodiment differs from the fifth embodimentonly in part of the control processing of the control device. Therefore,the description of the present embodiment will focus on the mattersdifferent from the fifth embodiment. Detailed descriptions of thematters identical to those in the fifth embodiment will be omitted.

In the fifth embodiment, the inverted pendulum mass point lateralmovement amount Pb_diff_y and the inverted pendulum mass point lateralvelocity Pb_diff_dot_y for the inverted pendulum mass point 71 in thetwo-mass-point model were used as the controlled state quantities.

In contrast, in the present embodiment, the roll angle ϕb of the vehiclebody 202 and its temporal change rate, or, the roll angular velocityϕb_dot are used as the controlled state quantities.

Described below more specifically, the control device 260 in the presentembodiment includes, as functions implemented when the CPU executesinstalled programs (functions implemented by software) or as functionsimplemented by hardware configurations, the functions shown by the blockdiagram in FIG. 39.

That is, the control device 260 includes: a roll angular velocitydetecting section 300 which calculates a differential (temporal changerate) of the detected roll angle ϕb_act of the vehicle body 202 as adetected roll angular velocity ϕb_dot_act, a rider's center-of-gravitylateral displacement index value calculating section 301 whichcalculates an estimated vehicle body inclination angle displacementϕb_err1 as the aforesaid rider's center-of-gravity lateral displacementindex value, and a desired posture state determining section 302 whichdetermines a desired roll angle ϕb_cmd and a desired roll angularvelocity ϕb_dot_cmd of the vehicle body 202.

Here, the estimated vehicle body inclination angle displacement ϕb_err1has the same technical meaning as that in the third or fourthembodiment.

The control device 260 further includes a rider-steering-based rollmanipulated variable calculating section 308 which calculates arider-steering-based roll manipulated variable ϕb_err2 for causing theroll angle ϕb of the vehicle body 202 to approach an inclination angleappropriate to the steering force of the front wheels 203 f caused bythe operator's manipulation of the handlebar 220.

In the present embodiment, the rider-steering-based roll manipulatedvariable ϕb_err2 is a correction amount for correcting the desired rollangle ϕb_cmd.

The control device 260 further includes a posture control arithmeticsection 303 which determines a desired posture manipulation momentMsum_cmd as a control input (manipulated variable) for controlling theposture in the roll direction of the vehicle body 202, and a desiredtraveling speed determining section 287 which determines a desiredtraveling speed Vox_cmd. The desired traveling speed determining section287 is the same as that in the fifth (or first) embodiment.

In the present embodiment, the processing in the rider'scenter-of-gravity lateral displacement index value calculating section301, the desired posture state determining section 302, therider-steering-based roll manipulated variable calculating section 308,and the posture control arithmetic section 303 are carried out, at eachcontrol processing cycle, in the following manner.

First, the desired posture state determining section 302 determines, asthe desired roll angle ϕb_cmd, a roll angle ϕb_lean which is calculatedby the expression (36a) explained above in conjunction with the fifthembodiment, for example. The section 302 sets the desired roll angularvelocity ϕb_dot_cmd to zero, for example. It should be noted that thedesired roll angular velocity ϕb_dot_cmd may be determined variably inaccordance with, for example, the detected steering angle δf_act.

Further, the desired roll angle ϕb_cmd may be set to zero, for example.Alternatively, the desired roll angle ϕb_cmd may be determined variablyin accordance with, for example, the detected steering angle δf_act.

The rider's center-of-gravity lateral displacement index valuecalculating section 301 receives, as shown in FIG. 40, a detected rollangle ϕb_act, a detected steering angle δf_act, an estimated front-wheelrotational transfer velocity Vf_act, and a last time's value Msum_cmd_p(determined in the last time's control processing cycle) of the desiredposture manipulation moment Msum_cmd. It should be noted that Msum_cmd_pcorresponds to a pseudo estimate (observed value) of the moment (posturemanipulation moment) in the roll direction acting on the vehicle body202 by the driving force of the vehicle-body leaning actuator 209.

The rider's center-of-gravity lateral displacement index valuecalculating section 301 calculates an estimated vehicle body inclinationangle displacement ϕb_err1 as a rider's center-of-gravity lateraldisplacement index value, through the arithmetic processing shown by theblock and line diagram in FIG. 40. In this case, the rider'scenter-of-gravity lateral displacement index value calculating section301 is configured as an observer, as in the fifth embodiment.

Specifically, the rider's center-of-gravity lateral displacement indexvalue calculating section 301 calculates an estimate of the roll momentinertial force component Mi and an estimate of the roll moment floorreaction force component Mp by a roll moment inertial force componentcalculating section 301-2 and a roll moment floor reaction forcecomponent calculating section 301-3, respectively, on the basis of theinput values of δf_act and Vf_act.

In this case, the roll moment inertial force component calculatingsection 301-2 calculates an estimate of the roll moment inertial forcecomponent Mi by the arithmetic processing similar to that in the fifthembodiment. More specifically, the roll moment inertial force componentcalculating section 301-2 calculates the estimate of Mi by performingthe arithmetic processing of the above expressions (33a) to (33e) and ofthe following expression (33f′) which is obtained by replacing m1*h′ onthe right side of the above expression (33f) with m*h.Mi=(Voy_dot_act+ωz_act*Vox_act)*m*h  (33f)

Further, the roll moment floor reaction force component calculatingsection 301-3 calculates an estimate of the roll moment floor reactionforce component Mp by performing the arithmetic processing of the aboveexpression (34a) in the arithmetic processing of the roll moment floorreaction force component calculating section 283-3 in the fifthembodiment, and of the following expression (34d) which is obtained bysetting p² in the expression (34c) to zero.Mp=Pfy(δf_act)*(Lr/L)*m*g  (34d)

The rider's center-of-gravity lateral displacement index valuecalculating section 301 then performs a dynamics computation of thefollowing expression (40a) in a processing section 301-4, on the basisof the estimates of Mi and Mp, the input value of ϕb_act, a value (lasttime's value) ϕb_err1_p of the estimated vehicle body inclination angledisplacement ϕb_err1 calculated in the last time's control processingcycle, and the last time's value Msum_cmd_p of Msum_cmd, to therebycalculate an estimate of an inclination angular acceleration ϕb_dot2 ofthe vehicle body 202.

Stated differently, the last time's value ϕb_err1_p corresponds to thelatest one of the estimated vehicle body inclination angle displacementsϕb_err1 calculated up to then.ϕb_dot2=(m*g*h*(ϕb_act+ϕb_err1_p)+Mp+Mi+Msum_cmd_p)/J  (40a)

In the expression (40a), J is a predetermined, set value of the inertiaof the entirety of the three-wheeled vehicle 201 (including theoperator) about the X axis of the aforesaid XYZ coordinate system.

Then, the rider's center-of-gravity lateral displacement index valuecalculating section 301 integrates, in a processing section 301-5,ϕb_dot2 calculated by the above expression (40a), to thereby calculate afirst estimated roll angular velocity ϕb_dot_1 as a first estimate ofthe roll angular velocity ϕb_dot of the vehicle body 202, as shown bythe following expression (40b).ϕb_dot_1=integral of ϕb_dot2  (40b)

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 301 performs, in a processing section 301-1, adifferential operation on the input value of ϕb_act, to calculate asecond estimated roll angular velocity ϕb_dot_2 as a second estimate ofthe roll angular velocity ϕb_dot of the vehicle body 202, as shown bythe following expression (40c).ϕb_dot2=differential (temporal change rate) of ϕb_act  (40c)

It should be noted that ϕb_dot_2 calculated by the expression (40c) isthe same as the detected roll angular velocity ϕb_dot_act calculated inthe aforesaid roll angular velocity detecting section 300. Therefore,the detected roll angular velocity ϕb_dot_act may be used, withoutmodification, as the second estimated roll angular velocity ϕb_dot_2.

Here, the first estimated roll angular velocity ϕb_dot_1 calculated bythe above expression (40b) corresponds to an estimate of the roll angleof the vehicle body 202 calculated on the assumption that the overallcenter of gravity G of the three-wheeled vehicle 201 is on the plane ofsymmetry of the vehicle body 202.

Therefore, the deviation between the second estimated roll angularvelocity ϕb_dot_2 and the first estimated roll angular velocityϕb_dot_1, calculated dynamically according to the above expressions(40a) and (40b), becomes a value depending on the vehicle bodyinclination angle displacement amount caused by the lateral displacementof the center of gravity of the operator.

Therefore, the rider's center-of-gravity lateral displacement indexvalue calculating section 301 calculates the estimated vehicle bodyinclination angle displacement ϕb_err1, in a processing section 301-6,by the arithmetic processing of the following expression (40d).ϕb_err1=(ϕb_dot_2−ϕb_dot_)*Kestm*J/(m*g*h)  (40d)

Kestm used in the arithmetic processing of this expression (40d) is apredetermined gain of a predetermined value. It should be noted thatKestm*J/(m*g*h) in the expression (40d) may be set in advance as asingle gain value.

Supplementally, in the block and line diagram in FIG. 40, a last time'svalue (=ϕb_err1_p*m*g*h) of (ϕb_dot_2−ϕb_dot_1)*Kestm*J is input to theprocessing section 301-4 from the processing section 301-6.Alternatively, a last time's value ϕb_err1_p of the estimated vehiclebody inclination angle displacement ϕb_err1, for example, may be inputdirectly to the processing section 301-4.

In the above-described manner, the rider's center-of-gravity lateraldisplacement index value calculating section 301 in the presentembodiment calculates the estimates of Mi and Mp, and uses theseestimates, the detected vehicle body roll angle ϕb_act, and the lasttime's value Msum_cmd_p of Msum_cmd, as a pseudo estimate of the posturemanipulation moment acted on the vehicle body 202 by the vehicle-bodyleaning actuator 209, to perform the arithmetic processing of theexpressions (40a) to (40d), to thereby calculate the estimated vehiclebody inclination angle displacement ϕb_err1.

Next, the rider-steering-based roll manipulated variable calculatingsection 308 receives a detected steering angle δb_act and a detectedhandlebar torque Th_act, as shown in FIG. 41.

The rider-steering-based roll manipulated variable calculating section308 calculates a rider-steering-based roll manipulated variable ϕb_err2as a correction amount of the desired roll angle ϕb_cmd, by thearithmetic processing shown by the block and line diagram in FIG. 41.

Specifically, the rider-steering-based roll manipulated variablecalculating section 308 calculates the rider-steering-based rollmanipulated variable ϕb_err2 by the arithmetic processing of the aboveexpression (37a) in the fifth embodiment and of the following expression(37b′) which is obtained by replacing m1*g on the right side of theexpression (37b) with m*g*h.ϕb_err2=Kcmv*Tstr*(1(m*g*h))  (37b′)

In this manner, the rider-steering-based roll manipulated variableϕb_err2 for correcting the desired roll angle ϕb_cmd so as to make thevehicle body 202 lean according to the steering torque Tstr of the frontwheels 203 f by the operator's manipulation of the handlebar 220 iscalculated.

In the above-described manner, the rider-steering-based roll manipulatedvariable calculating section 308 calculates the rider-steering-basedroll manipulated variable ϕb_err2 by the arithmetic processing of theexpressions (37a) and (37b′).

Next, the posture control arithmetic section 303 receives, as shown inFIG. 42, a desired roll angle ϕb_cmd and a desired roll angular velocityϕb_dot_cmd determined in the desired posture state determining section302, a detected roll angle ϕb_act and a detected roll angular velocityϕb_dot_act, an estimated vehicle body inclination angle displacementϕb_err1 calculated in the rider's center-of-gravity lateral displacementindex value calculating section 301, and a rider-steering-based rollmanipulated variable ϕb_err2 calculated in the rider-steering-based rollmanipulated variable calculating section 308.

The posture control arithmetic section 303 uses these input values toperform the arithmetic processing shown by the block and line diagram inFIG. 42, to determine a desired posture manipulation moment Msum_cmd.

That is, the posture control arithmetic section 303 calculates thedesired posture manipulation moment Msum_cmd by the arithmeticprocessing of the following expression (41).Msum_cmd=−K1*((ϕb_cmd+Kdstb1*ϕb_err1−Kdstb2*ϕb_err2)−ϕb_act)−K2*(ϕb_dot_cmd−ϕb_dot_act)  (41)Here, Kdstb1, Kdstb2, K1, and K2 in the expression (41) are gains ofpredetermined values. The values of these gains Kdstb1, Kdstb2, K1, andK2 are set variably in accordance with, for example, the estimatedtraveling speed Vox_act of the three-wheeled vehicle 201, or thedetected steering angle δf_act.

In this case, in the present embodiment, the values of the gains Kdstb1,Kdstb2, K1, and K2 are set such that the moment in the roll directionacting on the vehicle body 202 by the actuation of the vehicle-bodyleaning actuator 209 according to Msum_cmd will become not so large(such that the operator can lean the vehicle body 202 in the rolldirection relatively easily by shifting his/her weight).

Further, the magnitudes of the gains Kdstb1, Kdstb2, K1, and K2 are allset such that they vary in accordance with the estimated traveling speedVox_act of the three-wheeled vehicle 201.

For example, the magnitudes of the gains Kdstb2, K1, and K2 are all setvariably such that they become smaller as the estimated traveling speedVox_act of the three-wheeled vehicle 201 is higher.

It should be noted that the values of the gains Kdstb1, Kdstb2, K1, andK2 are generally different from those in the fifth embodiment.

Kdstb1*ϕb_err1 in the expression (41) is a correction amount, applicablein a lean-out or lean-in state, for correcting the desired roll angleϕb_cmd, determined in the desired posture state determining section 302,in such a way as to increase the lateral displacement of the center ofgravity of the operator (thereby enhancing the lean-out or lean-instate).

Further, Kdstb2*b_err2 in the expression (41) is a correction amount forcorrecting the desired roll angle ϕb_cmd so as to make the vehicle body202 lean according to the steering force of the front wheels 203 f bythe operator.

Further, in the expression (41),−K1*((ϕb_cmd+Kdstb1*ϕb_err1−Kdstb2*ϕb_err2)−ϕb_act) is a feedbackmanipulated variable component having the function of causing thedeviation between the desired value(ϕb_cmd+Kdstb1*ϕb_err1−Kdstb2*ϕb_err2), obtained by correcting ϕb_cmd,and the detected roll angle ϕb_act to approach zero, and−K2*(ϕb_dot_cmd−ϕb_dot_act) is a feedback manipulated variable componenthaving the function of causing the deviation (ϕb_dot_cmd−ϕb_dot_act) toapproach zero.

Of −K1*((ϕb_cmd+Kdstb1*ϕb_err1−Kdstb2*ϕb_err2)−ϕb_act),−K1*Kdstb1*ϕb_err1 is a manipulated variable component having thefunction of applying a moment in the direction of further increasing themagnitude of ϕb_err1 (a moment in the roll direction) to the vehiclebody 202.

In the present embodiment, in the case where the magnitude (absolutevalue) of ϕb_err1 is smaller than a predetermined value (in the casewhere ϕb_err1 takes a value in the dead band near zero), the posturecontrol arithmetic section 303 performs the computation of the aboveexpression (41) by setting Kdstb1*ϕb_err1=0. Therefore, the moment inthe direction of further increasing the magnitude of ϕb_err1 is appliedto the vehicle body 202 on the condition that the magnitude of ϕb_err1is the predetermined value or greater.

In the above-described manner, the posture control arithmetic section303 performs the arithmetic processing of the above expression (41), ateach control processing cycle, to thereby calculate the desired posturemanipulation moment Msum_cmd.

The present embodiment is identical to the fifth embodiment except forthe matters described above.

Here, the correspondence between the present embodiment and the presentinvention will be described supplementally.

In the present embodiment, the vehicle-body leaning actuator 209corresponds to the actuator in the present invention. In this case, thevehicle-body leaning actuator 209 primarily has the function as anactuator which causes the vehicle body 202 to swing in the rolldirection with respect to the road surface. The vehicle-body leaningactuator 209 also has the function as an actuator which moves the centerof gravity of the vehicle body 202 in the lateral direction (Y-axisdirection).

Further, the rider's center-of-gravity lateral displacement index valuecalculating section 301 corresponds to the center-of-gravitydisplacement degree index value determining section in the presentinvention. In this case, the estimated vehicle body inclination angledisplacement ϕb_err1 corresponds to the center-of-gravity displacementdegree index value in the present invention. Further, the position onthe plane of symmetry of the vehicle body 202 corresponds to thepredetermined reference position related to the position of the centerof gravity of the operator.

Further, the estimated front-wheel rotational transfer velocity Vf_act,the detected steering angle δf_act, the last time's value Msum_cmd_p(which corresponds to a pseudo estimate of posture manipulation moment)of the desired posture manipulation moment Msum_cmd, and the secondestimated roll angular velocity ϕb_dot_2 (=detected roll angularvelocity ϕb_dot_act) as a differential value of the detected roll angleϕb_act correspond to the observed values of the motional state of themobile body (three-wheeled vehicle 201) used in the processing of thecenter-of-gravity displacement degree index value determining section(rider's center-of-gravity lateral displacement index value calculatingsection 301). In this case, ϕb_dot_2 corresponds to the observed valueof the inclination state quantity of the vehicle body 202.

Further, the above expressions (40a) and (40b) correspond to thedynamics computation in the present invention. The first estimated rollangular velocity ϕb_dot_1 calculated by the expression (40b) correspondsto the calculated value of the inclination state quantity of the vehiclebody 202.

It should be noted that the dynamics computation in this case becomesthe dynamics computation based on the dynamic model of the system madeup of the mass point of the mass m (mass point of the overall center ofgravity) and the inertia J.

Further, the rider-steering-based roll manipulated variable calculatingsection 308 includes the function as the steering force estimatingsection in the present invention. Specifically, the processing of theabove expression (37a) corresponds to the steering force estimatingsection.

The posture control arithmetic section 303 corresponds to the controlinput determining section in the present invention, and Msum_cmdcalculated by the posture control arithmetic section 303 corresponds tothe control input in the present invention.

The gain Kdstb1 in the above expression (41) performed by the posturecontrol arithmetic section 303 corresponds to the sensitivity of thechange in control input (Msum_cmd) to the change in center-of-gravitydisplacement degree index value (estimated vehicle body inclinationangle displacement ϕb_err1).

According to the sixth embodiment described above, it is possible toachieve the effects similar to those in the fifth embodiment. The fifthembodiment, however, is more advantageous than the sixth embodiment interms of improving the reliability of the posture control of the vehiclebody 202.

[Modifications]

Several modifications related to the above-described first through sixthembodiments will be described below.

In the first through fourth embodiments, two steering axes of the firststeering axis Cf1 and the second steering axis Cf2 were provided as thesteering axis of the front wheel 3 f (steered Wheel). The steering axisof the front wheel 3 f, however, may be only one steering axis (forexample, Cf1).

Furthermore, the steering mechanism 6 of the two-wheeled vehicle 1 mayhave a configuration different from that in the first embodiment. Forexample, the steering mechanism 6 may have a structure as illustrated inFIG. 8 or 10 in Japanese Patent Application Laid-Open No. 2014-184934.

In the first through fourth embodiments, the front wheel 3 f was steeredby the first steering actuator 15 and the second steering actuator 37for controlling the posture in the roll direction of the vehicle body 2.In the case where the rear wheel 3 r serves as a steered wheel which issteerable, however, the rear wheel 3 r may be steered by an actuator forcontrolling the posture in the roll direction of the vehicle body 2.

In the fifth and sixth embodiments, the three-wheeled vehicle 201 havingtwo front wheels 2031R, 203 fL was given as an example. The mobile bodyof the present invention, however, may be a three-wheeled vehicle havingtwo rear wheels.

Furthermore, the mobile body of the present invention may be afour-wheeled vehicle 401 having two front wheels 403 fR. 403 fL and tworear wheels 403 rR, 403 rL, as illustrated in FIGS. 43A, 43B, and 43C,for example.

The four-wheeled vehicle 401 has a vehicle body 402 having a boardingsection 404 for an operator, and the front wheels 403 fR and 403 fL,arranged on the right and left, and the rear wheels 403 rR and 403 rL,arranged on the right and left, are disposed on the front side and therear side, respectively, of the vehicle body 402.

In this four-wheeled vehicle 401, the configurations on the front sideof the vehicle body 402, including the front-wheel support mechanisms,are identical to those shown in FIGS. 28A to 28C. Therefore, thedescription of these configurations will be omitted.

The rear wheels 403 rL and 403 rR are rotatably and pivotally supported,via bearings or the like, by rear-wheel support mechanisms 405L and405R, respectively, which are disposed on the left and right sides atthe rear portion of the vehicle body 402.

The left and right rear-wheel support mechanisms 405L and 405R arecoupled via a parallel link 407 which is made up of an upper link 407 uand a lower link 407 d spaced apart in the up-and-down direction andextending in the lateral direction. Such a parallel link 407 is disposedon the front side and the rear side of the rear-wheel support mechanisms405L, 405R.

The upper link 407 u and the lower link 407 d of a parallel link 407have their center portions pivotally supported so as to be swingableabout the axes in the longitudinal direction with respect to the rearend portion of the vehicle body 402.

Therefore, when the vehicle body 402 is caused to lean, the parallellink 407 on the rear side comes to swing with respect to the vehiclebody 402, as with the parallel link on the front side of the vehiclebody 402. In this case, the rear wheels 403 rL and 403 rR lean similarlyto the front wheels 403 fR and 403 fL (in a manner similar to that shownin FIG. 29A).

In this mobile body 401, the posture in the roll direction of thevehicle body 402 can be controlled by the control processing similar tothat in the fifth or sixth embodiment.

Further, in the fifth and sixth embodiments, the vehicle body 202 wasallowed to lean (swing) with respect to the road surface by themechanism utilizing the parallel link 207. As the mechanism for makingthe vehicle body swing with respect to the road surface, however, themechanism illustrated in FIGS. 44 and 45, for example, may also beadopted.

The mobile body 501 illustrated in FIG. 44 is a three-wheeled vehiclewhich includes a vehicle body 502 having a boarding section (seat) 504for an operator, one front wheel 503 f (steered wheel) disposed on thefront side of the vehicle body 502, and two rear wheels 503 r, 503 rdisposed side by side in the lateral direction (direction perpendicularto the paper plane of FIG. 44) on the rear side of the vehicle body 502.

In this mobile body 501, the front wheel 503 f is supported by thevehicle body 502 via a front-wheel support mechanism 505 made up of afront fork and the like, in such a way as to be steerable throughmanipulation of a handlebar 513.

Further, in this mobile body 501, a power engine unit 521 serving as apower source of the mobile body 501 is disposed in a position betweenthe rear wheels 503 r, 503 r. In the illustrated example, the powerengine unit 521 is covered with a cover member 522 attached thereto.

The power engine unit 521 is connected to the rear wheels 503 r, 503 rsuch that a rotative driving force can be transmitted to the rear wheels503 r, 503 r from a power engine, which is configured with an engine, anelectric motor, or the like.

The power engine unit 521 is coupled to the vehicle body 502 via a rolldriving mechanism 523. The roll driving mechanism 523 couples the powerengine unit 521 to the vehicle body 502 in such a way as to allow thevehicle body 502 to swing (lean) in the roll direction with respect tothe road surface by the driving force of an actuator 533 included in theroll driving mechanism 523.

The roll driving mechanism 523 is configured as shown in FIG. 45, forexample. The longitudinal direction and lateral direction in FIG. 45correspond respectively to the longitudinal direction and lateraldirection (vehicle width direction) of the vehicle body 502.

Referring to FIG. 45, the roll driving mechanism 523 includes, as itsprimary components: a rear-wheel-side fixing unit 531 which is securedto the power engine unit 521, a rotary unit 532 which is assembled insuch a way as to be rotatable in the roll direction with respect to therear-wheel-side fixing unit 531, the actuator 533, and a powertransmission mechanism 534 which transmits the driving force (rotativedriving force) of the actuator 533 to the rotary unit 532.

The rear-wheel-side fixing unit 531 includes a pair of plate members535, 535 which are spaced apart from each other in the lateral directionand secured to the power engine unit 521 via screws and the like, and ashaft member 536 which is disposed between the plate members 535, 535 inthe state where its shaft center C1 extends in the longitudinaldirection. The shaft member 536 has its outer periphery secured to theplate members 535, 535.

The rotary unit 532 disposed on the front-end side of the shaft member536 is coupled to the shaft member 536, via bearings or the like, insuch a way as to be rotatable about the shaft center C1 of the shaftmember 536.

The rotary unit 532 extends frontward from the shaft member 536 side.The rotary unit 532 is coupled to the vehicle body 502 via mountingholes 537, 537 formed at bifurcated portions at the front-side end ofthe rotary unit 532, in such a way as to be swingable in the pitchdirection (about the axis in the lateral direction) with respect to thevehicle body 502.

This makes the vehicle body 502 swingable (in the roll direction) aboutthe shaft center C1 of the shaft member 536, and also swingable (in thepitch direction) about the shaft center of the mounting holes 537, 537,with respect to the rear wheels 503 r, 503 r (and, hence, with respectto the road surface with which the rear wheels 503 r, 503 r are incontact).

Further, an upper surface portion of the rotary unit 532 is coupled tothe vehicle body 502 via a damper 538 (shown in FIG. 44) which has oneend pivotally supported at a mounting hole 539 formed on the uppersurface portion. This damper 538 serves to damp or brake the swing inthe pitch direction of the rotary unit 532.

The actuator 533 is an actuator which makes the vehicle body 502 swingin the roll direction with respect to the road surface. It is made up ofan electric motor or a hydraulic motor, for example. The housing of theactuator 533 is secured to one of the plate members 535, 535 (to theplate member 535 on the right side in the figure) via the housing of aspeed reducer 541 attached to the actuator 533.

The power transmission mechanism 534 is configured to transmit therotative driving force input to the speed reducer 541 from the actuator533, to the rotary unit 532, via a coupling 544, a driving-side crankarm 545, a connection rod 546, and a driven-side crank arm 547.

More specifically, a ring-shaped plate 543 serving as an input sectionof the coupling 544 is secured to a tip end portion of an output shaft542 protruding frontward from the speed reducer 541. Further, theplate-shaped driving-side crank arm 545 serving as an output section ofthe coupling 544 is disposed behind the ring-shaped plate 543, spacedapart from the ring-shaped plate 543 in the shaft center direction ofthe output shaft 542. The driving-side crank arm 545 is supported on theouter periphery of the output shaft 542 via bearings or the like in sucha way as to be rotatable relative to the output shaft 542.

The coupling 544 is interposed between the ring-shaped plate 543 and thedriving-side crank arm 545. The coupling 544 has a structure in whichprojections and depressions formed on the respective surfaces of thedriving-side crank arm 545 and the ring-shaped plate 543 facing eachother are engaged via a plurality of elastic members 543 a of rubber orthe like. Therefore, the coupling 544 is configured to transmit therotative driving force between the ring-shaped plate 543 and thedriving-side crank arm 545 via the elastic force of the elastic members543 a.

The driven-side crank arm 547 is protrusively provided on the uppersurface portion of the rotary unit 532 such that it is aligned with thedriving-side crank arm 545, with a spacing therebetween in the lateraldirection. The driven-side crank arm 547 is coupled to the driving-sidecrank arm 545 via the connection rod 546.

With the power transmission mechanism 534 configured as described above,the rotative driving force, output from the actuator 533 via the speedreducer 541 to the output shaft 542, is transmitted via the ring-shapedplate 543, the coupling 544, the driving-side crank arm 545, theconnection rod 546, and the driven-side crank arm 547, to the rotaryunit 532, and further transmitted via the rotary unit 532 to the vehiclebody 502.

The rotative driving force transmitted from the actuator 533 to thevehicle body 502 in this manner causes a moment in the roll direction toact on the vehicle body 502, thus enabling the vehicle body 502 to swingin the roll direction.

Supplementally, as the actuator of the roll driving mechanism 523, anelectric or hydraulic linear actuator may be used instead of the rotaryactuator 533.

Further, as the power transmission mechanism 534 of the roll drivingmechanism 523, a mechanism which includes a plurality of gears or amechanism which transmits rotation via a belt or chain may be adopted.

In the mobile body 501 with the above-described structure as well, theactuator 533 can be controlled by the control processing similar to thatin the fifth or sixth embodiment, to thereby control the posture in theroll direction of the vehicle body 502.

It should be noted that the mobile body 501 shown in FIG. 44 is athree-wheeled vehicle having one front wheel 503 f and two rear wheels503 r. The mobile body having the roll driving mechanism 523 asdescribed above, however, may be a mobile body having two front wheelsand one rear wheel, or may be a four-wheeled vehicle having two frontwheels and two rear wheels.

Further, the technique (including the rider-steering-based rollmanipulated variable calculating section 288 or 308) of adjusting thecontrol input (desired posture manipulation moment Msum_cmd) forcontrolling the vehicle-body leaning actuator 209 according to thesteering force of a steered wheel (front wheel 203 f) by the operator,as in the fifth or sixth embodiment, is applicable, not only to thethree- or four-wheeled vehicles, but also to two-wheeled vehicles. Forexample, the technique is applicable to a two-wheeled vehicle whichallows the front-wheel support mechanism to swing in the roll directionwith respect to the vehicle body and the rear wheel, as seen in JapanesePatent Application Laid-Open No. 2006-182091.

What is claimed is:
 1. A mobile body including a vehicle body having aboarding section for an operator and freely tiltable in a roll directionwith respect to a road surface, front and rear wheels disposed spacedapart from each other in a longitudinal direction of the vehicle body,an actuator capable of causing a moment in the roll direction to act onthe vehicle body, and a control device configured to control theactuator, the control device comprising: a center-of-gravitydisplacement degree index value determining section which determines acenter-of-gravity displacement degree index value using an observedvalue of a motional state of the mobile body, the center-of-gravitydisplacement degree index value representing an estimate of a degree ofdisplacement of a center of gravity of the operator boarded on theboarding section in a lateral direction of the vehicle body from apredetermined reference position with respect to the vehicle body; and acontrol input determining section which determines a control input forcontrolling the actuator in accordance with the determinedcenter-of-gravity displacement degree index value in such a way as toincrease the degree of displacement of the center of gravity of theoperator indicated by the determined center-of-gravity displacementdegree index value in a state where the center of gravity of theoperator boarded on the boarding section is displaced from thepredetermined reference position, wherein the control device isconfigured to control the actuator in accordance with the determinedcontrol input, the observed value of the motional state used in thecenter-of-gravity displacement degree index value determining sectionincludes an observed value of an inclination state quantity representinga state of inclination of the vehicle body, the center-of-gravitydisplacement degree index value determining section is configured tosequentially determine the center-of-gravity displacement degree indexvalue, and also includes a section which calculates an estimate of theinclination state quantity through a dynamics computation using thedetermined center-of-gravity displacement degree index value, and thecenter-of-gravity displacement degree index value determining section isconfigured to update the center-of-gravity displacement degree indexvalue based on a deviation between the calculated value of theinclination state quantity and the observed value of the inclinationstate quantity.
 2. The mobile body according to claim 1, wherein theactuator is an actuator which steers a steered wheel, among the frontand rear wheels, so as to cause a ground contact point of the steeredwheel to move laterally.
 3. The mobile body according to claim 1,wherein the actuator is an actuator which moves a center of gravity ofthe vehicle body so as to cause a moment in the roll direction to act onthe vehicle body by a gravitational force acting on the vehicle body. 4.The mobile body according to claim 1, wherein the actuator is anactuator which causes the vehicle body to swing in the roll directionwith respect to the road surface.
 5. The mobile body according to claim4, wherein the control device further comprises a steering forceestimating section which estimates a steering force applied to a steeredwheel, among the front and rear wheels, as the operator boarded on theboarding section manipulates a handle for steering the steered wheel,and the control input determining section is configured to determine thecontrol input in accordance with the center-of-gravity displacementdegree index value and the estimated steering force.
 6. The mobile bodyaccording to claim 1, wherein the control input determining section isconfigured to determine the control input for controlling the actuatorin such a way as to increase the degree of displacement of the center ofgravity of the operator on a condition that a magnitude of the degree ofdisplacement of the center of gravity of the operator indicated by thedetermined center-of-gravity displacement degree index value is apredetermined value or greater.
 7. The mobile body according to claim 1,wherein the dynamics computation carried out by the center-of-gravitydisplacement degree index value determining section is a dynamicscomputation based on a dynamic model which expresses dynamics of themobile body by dynamics of a mass point system formed of an invertedpendulum mass point and a ground surface mass point, the invertedpendulum mass point moving in a horizontal direction above a contactground surface of the mobile body, in accordance with a change of aninclination angle in the roll direction of the vehicle body and a changeof a steering angle of a steered wheel among the front and rear wheels,the ground surface mass point moving horizontally on the contact groundsurface of the mobile body, in accordance with the change of thesteering angle of the steered wheel and independently of the change ofthe inclination angle in the roll direction of the vehicle body.
 8. Themobile body according to claim 1, wherein the dynamics computationcarried out by the center-of-gravity displacement degree index valuedetermining section is a dynamics computation based on a dynamic modelwhich expresses dynamics of the mobile body by dynamics of a systemformed of a mass point located at an overall center of gravity of themobile body and inertia in a direction about an axis in the longitudinaldirection of the mobile body.
 9. The mobile body according to claim 1,wherein the control input determining section is configured to determinethe control input such that sensitivity of a change in the control inputwith respect to a change in the center-of-gravity displacement degreeindex value varies in accordance with a traveling speed of the mobilebody.